Gamma-ray bursts and other sources of giant lightning discharges in protoplanetary systems

a r X i v :a s t r o -p h /0502010v 1 1 F e

b 2005

Astronomy &Astrophysics manuscript no.Gf232February 2,2008

(DOI:will be inserted by hand later)

Gamma-ray bursts and other sources of giant lightning

discharges in protoplanetary systems

B.McBreen 1,E.Winston 1,S.McBreen 2,and L.Hanlon 1

1

Department of Experimental Physics,University College,Dublin 4,Ireland.

2

Astrophysics Missions Division,Research Scienti?c Support Department of ESA,ESTEC,Noordwijk,The Netherlands.

Received /Accepted

Abstract.Lightning in the solar nebula is considered to be one of the probable sources for producing the chondrules that

are found in meteorites.Gamma-ray bursts (GRBs)provide a large ?ux of γ-rays that Compton scatter and create a charge separation in the gas because the electrons are displaced from the positive ions.The electric ?eld easily exceeds the breakdown value of ≈1V m ?1over distances of order 0.1AU.The energy in a giant lightning discharge exceeds a terrestrial lightning ?ash by a factor of ~1012.The predicted post-burst emission of γ-rays from accretion into the newly formed black hole or spin-down of the magnetar is su ?ciently intense to cause a lightning storm in the nebula that lasts for days and is more probable than the GRB because the radiation is beamed into a larger solid angle.The giant outbursts from nearby soft gamma-ray repeater sources (SGRs)are also capable of causing giant lightning discharges.The total amount of chondrules produced is in reasonable agreement with the observations of meteorites.Furthermore in the case of GRBs most chondrules were produced in a few major melting events by nearby GRBs and lightning occurred at e ?ectively the same time over the whole nebula,and provide accurate time markers to the formation of chondrules and evolution of the solar nebula.This model provides a reasonable explanation for the delay between the formation of calcium aluminium inclusions (CAIs)and chondrules.

Key words.Gamma Rays:bursts;Solar system:formation;Planetary systems:Protoplanetary disks;Planetary sys-

tems:formation

1.Introduction

Chondrules are typically millimetre-sized stony spherules that constitute the major component of most chondritic meteorites that originate in the region between Mars and Jupiter and which fall to Earth.They appear to have crystallised rapidly from free ?oating molten or partially molten drops.The large amount of chondrules present in chondritic meteorites and their possible crucial role in planet formation,highlights the importance of identifying the mechanism responsible for their formation.The heat source responsible for melting chondrules remains uncer-tain and proposed processes have been recently reviewed by Boss (1996)and Rubin (2000).One of the earliest proposals for the formation of chondrules is lightning caused by turbulence in the solar nebula (Whipple 1966;Cameron 1966).Lightning is a widespread phenomenon that is not restricted to terrestrial rainclouds (Uman 1987).Spacecraft have detected lightning on Jupiter and other planets.This model is not favoured for chon-drule production for a number of reasons including the limita-tion to the build up of a large electrostatic potential by the gas conductivity,the breakdown potential of the gas and the avail-able energy source (Desch &Cuzzi 2000;Eisenhour &Buseck

2

as a function of energy in molecular hydrogen.Theγ-ray

is taken from the compilation of Cullen et al.(1989)and electron data from Berger&Seltzer(1964).

the dominant process in H2up to70MeV above which pair production and trident production overtake Compton scatter-ing and only27%ofγ-rays with energy of170MeV and5% at1GeV undergo Compton scattering.Forγ-rays with energy above a few MeV,the kinematics of Compton scattering are such that most of the energy is taken by the electron,which is scattered in the forward direction.An incoming pulse ofγ-rays in H2is gradually transformed into electrons that move further

into the nebula leaving a cloud of positive charge in its

wake.

Here we do not consider the scattered photons that also tend to move in the forward direction.The attenuation length ofγ-rays and range of electrons in H2is given in Fig.1;the range of the latter in H2is less thanγ-rays with the same energy.As the en-ergy increases,the range of the electrons become an increasing fraction of theγ-ray Compton attenuation length,thus facilitat-ing a larger charge separation.This process has similarities to nuclear explosions in the atmosphere(Longmire1978).

A charge separation will also occur with pair production because some positrons annihilate in?ight creating a moving excess of negative charge that leaves behind a positive excess in the gas(Askaryan1962;Jelley et al.1966).The cross-section for positron annihilation is about1Barn/ΓwhereΓ=E/m0c2. About10%of the positrons with energy E=400MeV will annihilate in?ight.In order to make progress with charge sep-aration it is necessary to adopt a model of the nebula.There is a reasonably well developed theory of the solar nebula including the formation of terrestrial and gas giant planets.The discov-eries of extrasolar planets and disks orbiting young stars are leading to the characterisation of protoplanetary disks around young stars.In most models of the solar nebula,after the early evolution of the Sun,accretion slows down and the nebula be-comes essentially quiescent.We adopt the power law relation-ship for the surface densityΣof the solar nebula as a function of radial distance r from the Sun given by

Σ=Σ0[r/1AU]n(1) whereΣ0has the normalising value of4250g cm?2at1.0AU and exponent n is-1.0(Cameron1995).The choice ofΣ0and midplane,H,in astronomical units(AUs)for two models with normalising values,Σ0and exponent n,withΣ0=4250g cm?2 and n=-1.0(solid line)andΣ0=1700g cm?2and n=-1.5 (dashed line)and for three radial distances of(a)1AU,(b)3 AU and(c)5AU.The diamonds and squares give path lengths of150and300g cm?2measured from the top of the nebula. n varies between the models of the solar nebula.Hayashi et al. (1985)proposedΣ0=1700and n=-1.5in the minimum-mass model of the solar nebula and these values are consistent with minimum-mass models of extrasolar nebula(Kuchner2004).

In conventional models it is usually assumed that lightning occurs in the dusty midplane of the nebula(Horanyi et al.1995; Love et al.1995).However a GRB will preferentially interact with the outer region of the nebula that is in the direction of the GRB source.Therefore it is necessary to model the vertical structure of the nebula to obtain the surface density perpendic-ular to the midplane.

In the thin disk approximation the midplane isothermal pressure is given by(Cameron1995)

P c=0.25Σ?c s(2) where c s is the speed of sound and?=(GM/r3)1

B.McBreen et al.:GRBs and giant lightning discharges3 midplane at3AU using the minimum mass model(Fig.2c

Fig.2b).

3.Prompt GRB emission and charge separation

The rate of GRBs when averaged over the Hubble

~4×10?7yr?1galaxy?1(Zhang&Meszaros2003).The

GRB rate is smaller due to the drastic decrease in star

tion at low redshifts and a value of0.25×10?7yr?1

is widely used at z=0.We adopt a value of10?7yr?1

for the GRB rate and~107years for the lifetime of a

toplanetary disk.Hence there is a probability near100%

any protoplanetary system will be irradiated by a GRB.

isotropic equivalent energy of GRBs is in the range5×

to greater then1054erg.A GRB with an output of1052

will deliver~106erg cm?2to a protoplanetary system

lies at a distance equal to a galactic radius of10kpc.The

energy emission extends to well above100MeV with a

trum compatible with an extension of the electron synchrotron component(Dingus2001).An anomalous radiation compo-nent in the energy band between~1-200MeV was discovered in GRB941017(Gonz′a lez et al.2003).This component varies independently of the prompt GRB emission from50keV-1 MeV and contains three times more energy.

To model the charge separation and electric?eld in the neb-ula,we adopt a GRB that gives106erg cm?2with10%of the energy between20MeV and100MeV,which is assumed to be in65MeVγ-rays that yield Compton scattered electrons with energy of50MeV.The incident?ux ofγ-rays is≈1013photons m?2and is attenuated exponentially in H2using a mass absorp-tion co-e?cient ofμ=1.33×10?2cm2g?1(Fig.3a(i)).The positive charge also declines exponentially in the same way be-cause each Compton event creates a positive ion.The electrons travel on average an additional10g cm?2into the nebula in-cluding only the ionization loss(Fig.3a(ii)).The path length is further reduced by a retarding electric?eld of1V m?1which is typical of the breakdown value(Fig.3a(iii)).The charge ex-cess is the di?erence between the two distributions(Fig.3b). The net positive charge is con?ned to a layer of thickness10 g cm?2whereas the negative charge is distributed over a much wider range.The net positive or negative charge is11%and has a value of q≈10?7C m?2.Two percent of the net nega-tive charge is beyond300g cm2and penetrates deeply into the nebula.

Electrical breakdown occurs when a normally insulating gas suddenly becomes conducting in a strong electric?eld.The gas pressure is particularly important because lower pressure reduces the voltage necessary for the discharge and increases the width of the discharge channel.Breakdown occurs when the electric?eld is strong enough that a free electron accu-mulates~1eV of energy between successive collisions with gas molecules(Pilipp et al.1992).This condition is given by eE s(nσ)?1≈1eV where E s is the discharge electric?eld,n is the number density of gas molecules andσ~10?15cm?2 is the collision cross section.E s has a value of~2.4×106 V m?1for air and~2.0×106V m?1for H2at atmospheric pressure(Love et al.1995).The measured value of E s in thun-derstorms is about a factor of10lower and this di?erence is the number of positive ions as a function of path length in H2 for an incident?ux of1013photons m?2(i).The number of electrons as a function of path length taking into account the ionization loss of10g cm?2(ii)and also including a retarding electric?eld of1V m?1(iii).(b)The charge excess as a func-tion of path length for the ionization loss(solid line)and also including the retarding electric?eld(broken line).The model used is for r=3AU andΣ0=4250g cm?2with n=-1.0. often attributed to energetic runaway electrons from cosmic rays or radionuclides that prematurely trigger the discharge (Gurevich et al.2001).The value of E s scales with pressure and has a value of20V m?1to1V m?1at pressures between 10?5and5×10?7of atmospheric pressure,typical of disks in planetary forming systems.E s could have a higher value in dust loaded regions near the midplane(Gibbard et al.1997). The Compton scattered electrons produce ions and electrons that increase the conductivity of the gas above that caused by cosmic rays and radionuclides(Desch&Cuzzi2000,Love et al.1995).The large scale and rapid formation of the charge separation prevents signi?cant discharging by the gas conduc-tivity.

The charge separation described in the nebula is analogous to a capacitor.The basic equation for a parallel plate capacitor yields the potential di?erence V=qd(?o)?1between the plates separated by a distance d.V attains a value of1014V for q= 10?7C m?2and a representative value of d=0.1AU.The elec-tric?eld is~104V m?1and greatly exceeds E s by a factor of at least103even for a GRB at a distance10kpc and~40for a similar GRB at the distance to the Large Magellanic Cloud. As the GRB interacts with the nebula,the charge separation creates a strong electric?eld that exceeds E s and triggers the discharge(Dwyer2003).The duration of the discharge is esti-mated at100s(Pilipp et al.1992).The average current in the channel is~1011A if half of the excess charge from an area~d2?ows down the channel in100s.The width of the lightning channel depends on the gas pressure and has an estimated value

4 B.McBreen et al.:GRBs and giant lightning discharges

of~105cm assuming it is limited to a few thousand electron mean free paths(Pilipp et al.1992).

The total energy inγ-rays,over an area comparable in size to the charge separation of0.1AU,gives an upper limit of1029 erg to the energy dissipated in the channel and this exceeds a large terrestrial lightning?ash by~1012.We cannot exclude the possibility of repeated strikes over the lightning channel,a situation that is somewhat analogous to the stepped leaders and return strokes in terrestrial lightning.Furthermore there is the possibility that the lightning may fragment into many channels (Uman1987).The visible and ultraviolet radiation from the discharge heats and melts the precursor grains to form chon-drules out to a distance of~109cm from the discharge channel. The total amount of chondrules produced in the nebula within a radius of5AU is5×1020g assuming a GRB with106erg cm?2has105erg cm?2in65MeVγ-rays,2×1010erg g?1to heat and melt the precursor dustballs and an e?ciency of10?2 to convert theγ-ray energy to chondrules(Jones et al.2000). The amount of chondrules produced is too small to account for the total mass of~3×1024g in the asteroid belt and the value of~1027g when the asteroid belt was300times larger than at present.The mass of chondrules can be increased by3×104 to1.5×1025g for a GRB at a distance of300pc(×103)with a higher isotropic luminosity of1053erg(×10)and an anoma-lous MeV component as observed in GRB941017(×3).This model is not su?cient because there is evidence from com-pound chondrules(Wasson1993)and compositional gradients in chondrules(Wasson&Rubin2003)that they were melted several times requiring a repeating process.

4.GRB post-burst emission and other sources The afterglow continues for days and weeks after the GRB when the relativistic blast wave decelerates by sweeping up the external medium.Anomalies in the afterglow of some GRBs including the detection of GeVγ-rays that lasted for over90minutes after GRB940217(Hurley et al.1994)can be accounted for by post-burst emission.After the GRB there could be a more extended period in which energy is injected into the remnant.This activity may be caused by continued drainage of matter left over from the explosion into the newly formed black hole or the spin-down of a super-pulsar or mag-netar(Rees et al.2000).Theγ-ray post-burst emission has not been measured and we must rely on model computations (Ramirez-Ruiz2004).The relativistic out?ow from a super-pulsar interacts with photons from a binary companion or from the explosion.The emission is mostly inγ-rays and estimated at1048erg s?1immediately after the GRB that declines to1047 erg s?1after10hours and1045erg s?1after100hours.The emission is beamed into a large solid angle that is not well con-strained by the model and we estimate it covers10?1of the sky. The prompt GRB?reball emission is collimated into a much smaller angle that is estimated on average to be2×10?3of the sky(Frail et al.2001).The nebula is50times more likely to be irradiated by post-burst emission than by the GRB.

The model of GRB emission is not unique and in the case of a structured jet,where the energy density per unit solid angle falls away from the axis,the emission is beamed into a larger solid angle by a factor of about5(Zhang&Meszaros2003).In this case the post-burst emission is ten times more likely to im-pinge on the nebula than the GRB.The post-burst emission of up to1052erg inγ-rays is su?ciently intense to cause a major lightning storm in the disk that lasts for days or even weeks and up to50such events may occur over the lifetime of the disk. These?fty events,occurring at a distance of10kpc,will pro-duce5×1023g of chondrules assuming an e?ciency of10?2 for conversion ofγ-ray energy to chondrules.The largest mass of chondrules is produced by the post-burst emission from the nearest GRB;a burst100pc distant will produce1026g within a radius of5AU in a disk.Strong dependence on the distance between the GRB and the protoplanetary disk results in a wide range in the mass of chondrules produced.In the above esti-mates we have assumed that the charge separation is not re-moved by the conductivity provided by the ions and electrons produced by the Compton scattered electrons,cosmic-rays and radionuclides.This will only be correct if the post burst emis-sion is in short duration outbursts like the GRB emission.The post-burst emission is more likely to be highly variable in the case of continued and sporadic accretion into the newly formed Kerr black hole(McBreen et al.2002).

Soft gamma-ray repeaters(SGRs)are also a possible source of lightning in the nebula.The energy that drives the giant ?ares(>1044erg)such as the1979March5event from SNR N49may be caused by a sudden large scale arrange-ment of the magnetic?eld which releases magnetic energy (Thompson&Duncan1996).The extreme possibility is that the entire dipole moment is destroyed in a single event releas-ing~1047erg(Eichler2002).The rate of such events could be as high as the rate of magnetar production~10?3yr?1and ~104such events could occur over the lifetime of the neb-ula.About10to100of these SGR explosions should be close enough to generate lightning in the disk and each one produce a small amount of chondrules,but the overall contribution of SGRs is much smaller than that of GRBs.

Other nearby and less variableγ-ray sources such as quasars,microquasars and powerful x-ray binaries(Mirabel& Rodriguez1999)might be expected to generate charge separa-tion and lightning.They require a much longer time of~105s to generate an electric?eld that can exceed E s,but the gas con-ductivity may limit the electric?eld to below this value.There is su?cient energy in these sources to produce large amounts of chondrules provided a method is found to limit the gas con-ductivity.The same limitation has been noted in other models of charge separation and lightning in the protoplanetary disk (Desch&Cuzzi2000,Gibbard et al.1997,Love et al.1995).

5.Discussion

GRBs and other sources are capable of producing signi?cant quantities of chondrules in protoplanetary systems anywhere in the disk of a galaxy.Stars form in giant molecular clouds of size about100pc and hence there is a higher than average probability it will contain massive stars that produce GRBs and SGRs and irradiate protoplanetary systems in the same cloud to form large amounts of chondrules.

B.McBreen et al.:GRBs and giant lightning discharges5

Compound chondrules consist of a primary that solidi-?ed?rst and one or more secondaries attached to the pri-mary(Wasson1993;Wasson&Rubin2003).Sibling com-pound chondrules have very similar textures and composi-tions and most,perhaps all,consist of chondrules melted in the same event.If this event is identi?ed with a nearby GRB, the chondrules would have been produced all across the disk and should provide a simultaneous time marker between sib-ling chondrules in di?erent meteorites.If the chondrules were produced by GRBs,the di?erences between the composition of meteorites are due to compositionally segmented regions of the nebula.The independent compound chondrules probably were produced in two separate events and it may be possible to de-termine the order and frequency of the GRB events from the meteorite record.

The magneto-rotational instability(MRI)provides an un-derstanding of radial mixing and turbulence in the disk (Balbus&Hawley1998).Turbulence can concentrate dust par-ticles of a particular size to spatial densities well above their background values(Cuzzi et al.2001;Wood1997).A large amount of chondrules can then be produced by lightning and provide an explanation for the large quantity of compound chondrules in meteorites.The magnetic?eld in the nebula must be well coupled to matter for MRI to be e?ective and this con-dition was satis?ed close to the Sun and beyond10AU where cosmic ray ionization may su?ce to maintain a signi?cant amount of ionization.The magnetic?eld during chondrule for-mation is not well constrained by the meteoritic evidence and seems to have a value between1and10gauss(Sugiura et al. 1979;Jones et al.2000).A magnetic?eld of this magnitude is signi?cant because it would channel Compton scattered elec-trons into regions of enhanced magnetic?eld,such as MRIs, and possibly cause lightning between regions in the disk which is analogous to cloud to cloud lightning in the Earth’s atmo-sphere.

The26Al/27Al ratio of CAIs in meteorites has a value of5×10?5whereas in chondrules the ratio has a much smaller value (Jones et al.2000;Cameron1995).The simplest explanation is that there was an interval of at least a million years between the formation of CAIs and chondrules.Chondrules should have formed preferentially late in the development of the disk after the Sun had stripped away most of the gas and allowed theγ-rays to penetrate closer to the midplane.This e?ect is more important in models of the disk with more than the minimum mass as shown in Fig.2.The penetration of the disk byγ-rays is easier beyond the snowline at about5AU because the disk is less massive.Chondrules produced beyond about5AU may have formed earlier and hence could contain26Al.

GRBs in the galaxy a?ect the Earths atmosphere(Thorsett 1995;Kurt&Zaidel1996;Scalo&Wheeler2002)and these events may be responsible for mass extinctions(Dar et al. 1998;Melott et al.2004;Thomas et al.2004).Fortunately the rate of GRBs is very low in our galaxy.However a GRB can reveal protoplanetary systems in other galaxies by transient in-frared emission from the melting chondrules and optical emis-sion from the gas(Duggan et al.2003;McBreen&Hanlon 1999).These events may be detectable for hundreds of years after the GRB when the expanding shell or cones of radiation interacts with protoplanetary systems.

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another的用法

an other others the other the others等。 1 one...the other翻译为一个...另一个...含义是有范畴的共2个2个部分2个人等。 例题I’ve got two tickets for tonight’s concert. One is for me _________ is for you. A other B the other C others D an other 答案D 2 one/some/several... another翻译为一个/一些/几个...另一个...含义中没有范畴可以无限增加。 例句You have had several cakes. Do you really want an other one Neither of the hats doesn’t look good on my daughter. Would you give me an other one 3 some...others...翻译为一些...其它的指剩余的大部分... 含义中没有范畴因为还有部分未提及。 例句/题A few students are playing soccer while others are watching them. 操场上一般不有只踢球和看球的人可能还有做其它活动的人。We should help_____when they are in trouble. A other B the others C others D the other我们不可能帮助除我们以外的所有人所以答案是C。 4 one...the others...翻译为一个...其余的指剩余的全部... 含义是有范畴的. 例句The minotor will go to the Teachers’ Office the others will stay in the classroom. 5some...the others...翻译为一些...其余的指剩余的全部... 含义是有范畴的. 例句Four of the ten boys are standing and the others are sitting round them.

another 的用法

1. another可视为由“an+other”构成,但总是写成一个词,不能写成an other;其后一般只接单数可数名词,不接复数名词或不可数名词。another有两个基本意义: (1) 外加的,同样的。如: Don’t say another word. 不要再说了。 Let me have another cup of tea. 给我再来一杯茶。 (2) 不同的,另外的。如: That’s another Story. 那是另一码事。 Give me another cup. This one’s cracked. 请给我换个杯子,这个裂了。 If I were you, I should get another lawyer. 如果我是你,我就请别的律师。 这样用的another表泛指。比较: Give me another (one). 另外给我一个。(表泛指) Give me the other (one). 给我另外那个。(表特指) 2. 在通常情况下,another 后不能接复数名词或不可数名词,但是若复数名词之前有few 或数词修饰,或不可数名词之前有piece of 之类的单位词时等,则可以与another 连用。如: I could go on for another two hours. 我再讲两个小时都讲不完。 I need another few days before l can make up my mind. 我还需几天才能决定。

3. one 有时可与another 对照使用。如: One (boy) wanted to read, and another wanted to watch TV. 一个(男孩)想看书,另一个则想看电视。 One day he wanted his lunch early, another day he wanted it late. 他一天要早点吃午饭,另一天又要晚点吃午饭。 4. 习语one after another意为“一个接一个地”“相继地”“依次地”,在句中主要用作状语。如: Planes took off one after another. 飞机陆续起飞。 One after another all his plans have failed. 他的计划都一一失败了。有时也可用作主语或宾语。如: One after another began to choke, and at the end all the women were weeping. 人们一个接一个哽咽起来,到结束的时候妇女们全都哭了。注意,该结构多用于三者或三者以上的“依次”,如指两者“依次”,则通常用one after the other。如: The boy showed me his dirty hands one after the other. 那男孩把他脏兮兮的手依序伸给我看。 5. one another 与each other:两者均表示“彼此”“互相”,原认为one another 用于三者或三者以上,each other 用于两者,但在现代英语中,两者常可换用。值得注意的是,“互相”一词,在中文里给人的感觉好像是副词,但其实它们是代词,因此它们在句不用作状语,若用于不及物动词之后时,要考虑添加适合的介词。如: We don’t always agree with one another [each other]. 我们的意见并

other--the-other--another-与-others-的用法区别、练习题及参考答案

other, the other, another 与 others 的用法区别 (1) 指复数时,若泛指用 other(后接复数名词),若特指用 the other(后接复数名词): There are other ways of doing it. 做这事还有其他的办法。Where are the other students 其他同学在哪里 (2) others 永远表示复数意义,且其后不能再接名词。其用法大致相 当于“other+复数名词”,同样地 the others 大致相当于“t he other+复数名词”: Show me some others. 再拿一些给我看。He died so that others might live. 他牺牲了自己使别人能够活下来。 I was tired, and so were the others. 我累了,其他人也一样。 — He is more careful than the others. 他比其他人更仔细。 Lei Feng is always ready to help others.雷锋总是乐于助人。(3) another一般只能表单数,且其后接名词时也只能接单数名词。但 是若其后有数词或 few 修饰时,则也可接复数名词: Have another piece of cake. 再吃一块蛋糕。 I’ve got another three minutes. 我还有三分钟。 (4) 与 some 对比使用时,用 others(此时与 some 同义): Some say yes, and others say no. 有人说对,有人说不对。

代词another和other的用法及练习

代词三 四、other的用法:other, another, others, the other, the others的用法区别 基本用法 other: other+ 复数名词( other student s) another: . another +单数名词, “另一个”(数目不清楚) the other: The other +复数名词= the others “其他的人或物”(指确定范围内剩下的全部) others (别人):其后不能带名词,代换上文中提及的可数名词(复数,泛指) the others:代词,其后不能带名词,代换上文中提及的可数名词(复数,定指); 考点要求注意两个句式、一个搭配和两个区别 1、两个句式的用法 (1)One … the other … 一个……另一个 ~ 注意:使用该句式时,其前应出现说明具体数量的数词two;如出现的数词大于two,one 可以根据实际情况调整成其它数词;如出现的数词减去one或调整后的数词后仍大于“1”时,the other应变为the others或“the other + 数词”(两个数词相加应等于所给数词)。 There are two apples here. One is for you, the other is for your sister. There are five apples here. Two are for you, the others are for your sister. There are five apples here. Two are for you, the other three are for your sister. (2)Some … others …一些……另一些 注意:使用该句式时,其前应出现说明不定数量的词语;如出现说明具体数量的数词,others前应加上the。 There are many people on the beach. Some are swimming, others are enjoying the sun. Mrs. Smith bought 25 books. Some were for her daughter, the others were for her son. 2、一个搭配:any同other连用时应注意之点: Any others:any同单一的other连用,other应使用others; Any other + 单数名词:any后如还带有名词,用other,名词用单数; 【 Any of结构:any of后的other前应加the,如含名词用other,名词用复数;如不含名词,用others。 Of all the cities in China, Shanghai is bigger than any others. Of all the cities in China, Shanghai is bigger than any other city. Of all the cities in China, Shanghai is bigger than any of the others. Of all the cities in China, Shanghai is bigger than any of the other cities. 3、两个区别:(1)同数词连用时another和more的区别 another用于数词前,more用于数词后。(鞍前马后)

other,another,others,the others,the other的用法和区别

other,another,others,the others,the other的用法和区别 other及其变化形式在初中教材中多次出现,而且它的变化形式很多,有以下几种:the other, others, the others, another 等。它们的用法现归纳如下; 1.other可作形容词或代词,做形容词时,意思是“别的,其他”,泛指“其他的(人或物)”。如: Do you have any other question(s)? 你还有其他问题吗? Ask some other people. 问问别人吧! Put it in your other hand. 把它放在你另一只手里。 2.the other指两个人或物中的一个时,只能用the other,不能用another,此时的other作代词。如:

He has two daughters. One is a nurse, the other is a worker. 他有两个女儿,一个是护士,另一个是工人。 the other后可加单数名词,也可加复数名词,此时的other作形容词。如: On the other side of the street,there is a tall tree. 在街道的另一边,有一棵大树。 Mary is much taller than the other girls. 玛丽比其他的女孩高得多。 He lives on the other side of the river. 他住在河的对岸。 3.others是other的复数形式,泛指“另外几个”,“其余的”。在句中可作主语、宾语。如: Some of us like singing and dancing, others go in for sports. 我们一些人喜欢唱歌和跳舞,其余的从事体育活动。 Give me some others, please. 请给我别的东西吧! There are no others. 没有别的了。 4.the others意思是“其他东西,其余的人”。特指某一范围内的“其他的(人或物)”。是the other的复数形式。如: Two boys will go to the zoo, and the others will stay at home. 两个男孩将去动物园,其余的留在家里。 the others=the other +复数名词,这在第2条中已经有所介绍。 5.another=an+ other,既可作形容词,也可作代词,只能用于三个或更多的人或物,泛指同类事物中的三者或三者以上的“另一个”,只能代替或修饰单数可数名词。如:

不定代词 other , another 的用法

不定代词other , another 的用法 1. Some people hope to be more successful while A simple want to feel more comfortable. A. the others B. others C. the other D. another 2. I have three pens. One is red, C two are black. A. another B. other C. the other D. the others 3.Mr Smith has two sons, D is a soldier, ______ is a doctor. A. One, another B. One, other C. This, the other D. One, the other 4. Children should be taught how to get along with C . A. another B. other C. others D. any other 5. There are many people in the park now. Some are boating, __D___ are walking along the lake. A. The other B. Other C. The others D.Others 6. The glass is broken. Go and get __B_____ . A. other B. another one C. others D. the other 三单元复习与提高 1.Liu Xiang ia an Olympic winner in the __B_____ hurdles (跨栏) . We are proud of him. A. 110-meters B. 110-meter C. 110 meter 2. –Dad, when will you be free? You agreed to go to the seaside with me four days ago. --I am sorry, Jean. But I think I will have a __B____ holiday soon. A. four day B. four—day C. four days D. four day 3. Enough sleep is good for health. If you _A___ for your favorite TV programs, you will feel sleepy. A. stay up B. set up(建立) C. pick up 4. She needs __A____ a rest, for she is working for over four hours. A. to have B. having C. have D. had 5.He is too young. He is not __A____ to join the army. A. old enough B. enough old C. too old D. old too 6. I must be back home _A_____ 8;00 pm/ A. by B. from C. for D. between 7.We were allowed __B___ here for a little longer time. A. staying B. to stay C. stayed D. to staying 8. The young man was often seen _A_____ by the lake. A. to draw B. to drawing C. draw D. drew ( 题中的主语与动词see为被动关系,而see用于被动语态时,结构为be seen to do …) 9.Our English teacher always tells us a verb must _B____ its subject in number and person. A. agree B. agree with C. agree to D. agree on Agree with ―同意某人说的话或建议‖ Agree to ―同意计划,建议,要求,条件等‖ Agree on ―就。。。达成一致‖ 10. Many students will be _B_____ if the class is boring. A. sleep B. sleepy C. sleeping D. slept 11. All the boys succeeded __C_____ the English examination. A. pass B. to pass C. passing D. on passing

another的用法

根据笔者多年英语教学经验,针对初中生学习状况,在此对易混知识点other, the other, others及another的用法做一个小结,希望能对广大英语爱好者有所帮助。 首先,根据这几个易混词特性列表如下: 一、下面对每个词的用法做一一归纳、小结,要注意区别各词的词性、含义及用法。 1、other 既可作形容词,也可作代词。作形容词时,意思为“另一方的、其它的”,泛指“其它的(人或事)”,后既可跟单数名词也可跟复数名词。eg: Do you have any other question(s)? 您还有其它的的问题不? Ask some other people、问问其她人。 Put it in your other hand、把它放在您的另一只手中。 2、the other (1) 指两个人或物中的一个时,只能用the other,不可用another,此时other作代词,谓语动词用单数形式。eg: He has two daughters, one is a nurse, the other is a teacher、 她有两个女儿,一个就是护士,另一个就是教师。 (2) 当the other后加名词时,既可加单数名词,也可加复数名词,此时other为形容词。eg: On the other side of the street, there is a tall tree、 在街的另一边有一棵很高的树。 Mary is much taller than the other girls、 玛丽比其她的女孩高得多。 3、others就是other的复数形式,泛指“另外几个”“其余的”, others等于other+复数名词,在句中作主语、宾语,作主语时,谓语动词与复数保持一致。eg: Some of us like singing and dancing, others go in for sports、 我们中的一些喜欢唱歌与跳舞,其她的从事体育活动。 Give me some others, please、请给我别的东西吧! There are no others、没有别的了。 4、another只能用于三个或更多的人或物,泛指同类事物中的三者或三者以上的“另一个”,既可作形容词,也可作代词,只能代替或修饰单数可数名词,前面不能加定冠词。eg: I don’t like this one, please show me another、 我不喜欢这一个,请给我瞧瞧另一个吧。 This book is too difficult for me,will you please give me another one? 这本书对我来说太难了,可以给我另一本不? He has got three books, one is a dictionary, another is a play, the third is a grammar、 她买了三本书,一本就是字典,另一本就是剧本,这有一本就是语法书。 To know is one thing and to do is another、知道就是一回事,做就是另一回事。 二、在区分清各个词的用法后,以下对一些相似点给予比较分析: 1、the other与another的用法比较 another就是许多中的另一个,the other就是指两个或两部分中的另外一个。another 就是泛指,the other就是特指。 (1) It’s another way of saying fast、

other用法讲解学习

在我们平时学习中,围绕着other及相关辨析词设计的考题相当多,实属中考英语的重难点。很多同学由于掌握的知识不够全面,理解不够清楚而丢分。下面从辨析考题的角度以点带题,以题衬点进行分析: I.theother;another;(the)others other后加名词单数时,前面必须有the,指“两者中另一个”,由于是特指,又是单数,需要限定词,因此theother后加名词单数特指“两者中另一个”(单数名词常省略),常用搭配为:One…,theother…(前提语境表明两者)。然而other后加名词复数时,根据语境,如果有明确的范围就用theother+名词复数(可以省略成theothers);如果没有明确的范围,即从广义上说的,那么就用other+名词复数(可以省略成others),常用搭配为:Some…,others…(如中考完形第46题)。Another+名词单数,指“三者或三者以上中另一个”。 填空练习 1.Thishatdoesn'tfit.I'dliketotry______。 2.Ihavetwobooks.OneisanEnglishbook,______isaChinesebook。 3.Shealwaysthinksof______andneverthinksofherself。 4.somechildrenlikeapples,______childrenlikebananas。 5.Thereare40studentsinourclass,threeareAmerican,______areChinese。 答案:1.another2.theother3.others4.other5.theothers II。表示“另外几个……”时other和another的区别 表示“另外几个……”时,用“数字+other+名词复数”或“another+数字+名词复数”。注意:数字放在other前或another后。如“另外三天”的表达为:

如何使用 another

如何使用another, other, others,the others 和the other 一、another可作形容词又可作代词,意为“另外、另一个”,主要指三个或三个以上的“另一个”,可以单独使用。作定语时,修饰可数名词单数,其前不加冠词,如: 1.Will you have another cup of tea?你再唱一杯茶吗? 2.I don’t like this hat, please show me another.我不喜欢这顶帽子,请另外拿一顶给我看。another的所有格为another’s。与another 有关的短语有:one another相互,one . . .after another 一个……接一个,from one . . . to another从一个……到另一个。 二、other可作形容词和代词,意为“另外的、别的”。 三、表示两个中的“另一个”时与the连用。可单独使用,也可用the other +可数名词单数。 1.The post office is on the other side of the street. 邮电局在街的另一边。 2.I have two sisters, one is a teacher, the other is a worker. 我有两个姐姐,一个是教师,另一个是工人。 四、指特定范围的“其它的”时,用the others或五、the other+名词复数。 如: 1.Where are the other boys of our class? 其余的人在哪儿? 2.Where are the other boys of our class? 我们班其余的男生在哪里? 六、无特定范围的“其它的”即泛指时,用others或+other复数名词。 I don’t like these, do you have any others?我不喜欢这些,你还有别的吗? Give me two other .给我两本其它的书。 Some are digging, some are planting, others are watering一些在挖土,一些在栽树,另一些在浇水。 七、Other的所有格为other’s (复数为others)。与other有关的短语有:the other day(另外一天),every other day每隔一天,one ofter the other(个个都,全部),on the other hand 另一方面,one . . .the others一个……其余的,some. . .others一些……其余的。

another与other的区别

another与other的区别。 ①Some students like English and other students (others) like physics. 有些学生喜欢英语,有些学生喜欢物理。 【解析】other表示“别的”,“另外的”,只能与复数名词连用。但other前有冠词the即可与单数名词连用。如: I have two pens. One is blue. The other (pen) is black. 我有两枝钢笔。一支是蓝色的,另一支是黑色的。 ②John did better than all the other players in the sport. 在那项运动中John比所有别的运动员都出色。 【解析】the other加复数名词指的是一定范围内“所有其余的人或事物”,是特指;而other加复数名词却是没有明确范围的“另外的人或事物”。如: We must think more of other comrades. 我们必须多想想别的同志。 ③This shirt is too large for me. Please show me another. 这件衬衫我穿太大。请另外拿一件我看看。(一般商店不会只有两件衬衫)【解析】another, the other作代词的用法。The other表示“两个数量中的另一个”,表示特指,总数为俩;another表示“总数为三个以上中任意的另一个”,表示泛指。如: His parents both work in a hospital. One is a doctor and the other is a nurse. 他父母都在一家医院工作。一个是医生,一个是护士。(父母为两个人) 其他习惯用法one anothe r, from one…to another, the other day = a few days ago,every other day/ week/year,some…, others…,如: I met Mr. Smith in the park the other day. 前几天我在公园里碰见了Smith先生。 While at the university, he went to the library every other day. 在大学时他每隔一天去图书馆一次。 Some people like football, others like volleyball. 有些人喜欢足球,有些人喜欢排球。 They are very different from one another. 他们互相之间差别很大。 When Americans moved from one place to another, they took their dialects with them. 当美国人从一个地方迁移到另一个地方时,

最新another的具体用法知识讲解

another,the other以及others ,the others都来源于other一词。从语法功能上看:another与the other既可作限定词,又可作不定代词,表示单数概念;而others与the others只能作不定代词,表示复数概念。由于它们均可作不定代词,且又源自同根,其意义十分靠近,一般英语初学者难免混淆其用法。本文就其区别试作分析比较如下: 一、another与the other 作限定词或不定代词,表示单数概念时,两者均可解为“另一(个)”,但实质含义迥然不同。 1. another:是an other的合并式,意为one more,an additional (one)或a different (one)。汉语可译为“又一(个)、另一(个)”等。用不定冠词,表示泛指含义,即指一系列人或事物中没有确定的另一个。因此,它用于其数目起码3个以上的场合(除“此”而外,至少另有两个存在)。例如: ——Here’s a seat for you, Wang Lin. 这儿有个座位给你,王琳。 —— No,thank you. There’s another (on e). 不,谢谢。那儿也有一个。 公共汽车上的座位起码不止3个,上述后句中的anther系指新提及的该座位以外的不定数目之一。又如: Don’t lose heart. Have another try. 别泄气,再试一次。 If this tie doesn’t suit you, choose another (one). 如果这条领带不适合你,另外选一条吧。 another作限定词时,也可与复数名词连用,表示“另外(若干)、又(若干)、再(若干)”意思。例如: In another three weeks, we have to stay in the camp to wait for them. 我们不得不呆在营地再等他们3个星期。 2. the other:意为the second of the two。汉语可译为“另外那个、另一(个)”等。用定冠词,表示特指含义,即指已知的两个人或事物中的另一个。因此,它用于其数目仅只两个的场合(除“此”而外,另仅有一个存在)。例如:——What’s on the two plates? 那两个盘子里有什么? ——There’s some fish on one plate. And there’s some bread on the other (one). 一个盘子里有鱼,而另一个有面包。 the other作限定词时,同样也可与复数名词连用,表示“其余的”意思。例如:Tom, Dick and I prepared for supper; the other ones cleaned the house. 汤姆,迪克和我准备做晚饭,其余的人打扫屋子。 二、others与the others 两者均作不定代词,表示复数概念,都带有“其他、其余、另外”等含义,但仍有差异。 1. others:意为some of the rest,即指在已知的一组人或事物中,除去某些后,余下的人或事物中的一部分。汉语可译为“另外一些、其他一些、别人”等。others 前用零冠词(zero article),即不用冠词,表示“部分”含义。例如: Some are carrying water, others are watering the trees.

other the other和another的用法

other、the other和another的用法: other意思是“另一”、“另一些”,有复数形式。在句子中可作主语、宾语和定语。another意思是“另外”、“又一个”,表示增加,在句中可作宾语和定语。 如:Some girls are singing under the big apple tree and others are sitting on the grass talking.(有些女孩在大苹果树下唱歌,别的就躺在草地上说话) / You have had several cakes. Do you really want another one?(你已经吃了好几块饼子了,你真的还要一块) / I want another four books.(我还要四本书) another(另外的,再一,又一)与the other(另外的一个) 主要从数量上区分,只有两个时用the other,在原先基础上增加用another。如:This is one of your socks. Where is the other one?(这是你的一只袜子,还有一只呢)/ I have eaten 4 cakes, but I still want another.(我已经吃了4块蛋糕,但是我还要以块。)

others与the others的主要区别:others指“剩余的人/物”(指大部分);the others指“其余的人/物”,(指全部)。 如:A few students are playing soccer while others are watching them.(有几个学生在踢足球,其他一些人在观看) / Two of the ten boys are standing and the others are sitting round them.(十个男孩中有两个站着,其他人都围着他们坐着。)

another的用法

another 的用法与语法 1. another可视为由“an+other”构成,但总是写成一个词,不能写成an other;其后一般只接单数 可数名词,不接复数名词或不可数名词。another有两个基本意义: (1) 外加的,同样的。如: Don’t say another word.不要再说了。 Let me have another cup of tea. 给我再来一杯茶。 (2) 不同的,另外的。如: That’s another Story.那是另一码事。 Give me another cup. This one’s cracked.请给我换个杯子,这个裂了。 If I were you, I should get another lawyer. 如果我是你,我就请别的律师。 这样用的another表泛指。比较: Give me another (one). 另外给我一个。(表泛指) Give me the other (one). 给我另外那个。(表特指) 2.在通常情况下,another 后不能接复数名词或不可数名词,但是若复数名词之前有 few 或数词修饰,或不可数名词之前有 piece of 之类的单位词时等,则可以与 another 连用。如: I could go on for another two hours. 我再讲两个小时都讲不完。 I need another few days before l can make up my mind. 我还需几天才能决定。 3. one 有时可与 another 对照使用。如: One (boy) wanted to read, and another wanted to watch TV. 一个(男孩)想看书,另一个则想看电视。 One day he wanted his lunch early, another day he wanted it late. 他一天要早点吃午饭,另一天又要晚 点吃午饭。 4.习语one after another意为“一个接一个地”“相继地”“依次地”,在句中主要用作状语。如: Planes took off one after another. 飞机陆续起飞。 One after another all his plans have failed. 他的计划都一一失败了。 有时也可用作主语或宾语。如: One after another began to choke, and at the end all the women were weeping. 人们一个接一个哽咽起来,到结束的时候妇女们全都哭了。

other和another……的用法

other others the other the others 和another 的用法 ①Some students like English and other students (others) like physics. 有些学生喜欢英语,有些学生喜欢物理。 【解析】other表示“别的”,“另外的”,只能与复数名词连用。但other前有冠词the即可与单数名词连用。如: I have two pens. One is blue. The other (pen) is black. 我有两枝钢笔。一支是蓝色的,另一支是黑色的。 ②John did better than all the other players in the sport. 在那项运动中John比所有别的运动员都出色。 【解析】the other加复数名词指的是一定范围内“所有其余的人或事物”,是特指;而other加复数名词却是没有明确范围的“另外的人或事物”。如: We must think more of other comrades. 我们必须多想想别的同志。 ③ This shirt is too large for me. Please show me another. 这件衬衫我穿太大。请另外拿一件我看看。(一般商店不会只有两件衬衫)【解析】another, the other作代词的用法。The other表示“两个数量中的另一个”,表示特指,总数为俩;another表示“总数为三个以上中任意的另一个”,表示泛指。如: His parents both work in a hospital. One is a doctor and the other is a nurse. 他父母都在一家医院工作。一个是医生,一个是护士。(父母为两个人) 其他习惯用法one another, from one…to another, the other day = a few days ago,every other day/ week/year,some…, others…,如: I met Mr. Smith in the park the other day.

英语语法运用other和another的用法

other,another,else,more的用法区别 other,another,more,else如何使用? 先将这些不定代词分为单、复数: 单数:another, (any) other, the other 复数:other+名词复数=others the other+名词复数=the others 单数部分中,用于表示与前边提到的一个不同,用another,两者当中的另一个用the other, 在比较级中表示比其他任何一个…., 用any other加单数名词。 复数部分中,其区别在于在others或the others。前面加the,表示除了前边提到的剩下 的全部,无the表示除了前边提到的剩下的大部分。 请做下面的题。 ( )1) Will you sh ow me _____? I don’t like it’s colour. ( )2) She has two computers. One is IBM PC 386 and _____ is IBM PC 586. ( )3) Tom runs faster than any ____ student in his class. ( )4) The students have English, Chinese, maths, biology and many _____ subjects. ( )5) Why are only three of you here in the classroom? Where are _______? ( )6) My cla ssmates come from different parts of the country. Some come from Shanghai, some from Tianjin and __ __ from Beijing. 答案:1) another 2) the other 3) other 4) other 5) the others 6) others else用在疑问代词和不定代词后面表示”其他的,别的” Who else wants to go to the park? I have nothing else to tell you.other后接单复数均可,other one或other two students. others只能作代词,意思是“其它的人、物、事等”,常用来泛指。 the other也是既能作形容词,又能作代词。但它一般用来表示总数为二时的“另外一个”,经常与one搭配。 other也能既作形容词又可作代词,意思是“别的,另外的”。 another作形容词时,是指在原有的基础上再加一(些),表示“再一(些)”或“另外一个(些)”的意思,在心理上至少有三个。 another还可作代词,意思与作形容词时一样。它前面不能加任何冠词,后面也不能加s the other表示两者中的另一个 another表示又一个 He is too short to get the apples on the tree。 He is so short that he can't get the apples on the tree。 He is not such tall as to get the apples on the tree。 other修饰名词,后面一般是复数名词,有时候是单数名词。如:I will come again some other day.(改天) We study Chinese, English and other lessons. another用于泛指3者以上的不定数目中的“另一个”,可以单独使用,但有时候后面可 以跟单数名词。如:I don't want this one. Please give me another. There is another seat. else用在what, who, where, 等的疑问代词或副词后面。如:What else do you want? more用在比较级前面

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