限时训练(30)答案
2021年内蒙古中考英语重点题型限时训练：完形填空+ 阅读理解(C)+ 选词填空+ 任务型阅读
完形填空+ 阅读理解(C)+ 选词填空+ 任务型阅读[限时:30分钟]Ⅰ.完形填空A teacher decided to have her class play a game. The teacher told each student to bring a plastic bag with a few potatoes in it to school. Each student would “name” their potatoes after people they did not like. 1, the number of potatoes would be 2depending on how many people each student hated.The next day, with their potatoes, all the students went to school 3the game. Some kids had just one or two potatoes, while others had as many as five or six. The teacher then told the children that they would have to carry their potatoes with 4wherever they went for one week. Several days 5, some of the students started to complain(抱怨), as their potatoes began to rot(腐烂) and 6bad. The students who carried 7potatoes began to get unsatisfied with the heavy bags.One week later, the game 8. The teacher asked, “How did you 9carrying around your potatoes for a week?”The students complained once again. The teacher simply smiled and said, “This is what it’s like to carry hatred(仇恨) in your heart. You have to carry it with you wherever you go. If you can’t tolerate(容忍) carrying rotten potatoes for one week, how can you imagine having 10in your heart for a whole lifetime? Forgive others and move on with your life.”()1.A.However B.In a wordC.ThereforeD.After all()2.A.different B.similarC.the sameD.small()3.A.to watch B.to join inC.to winD.to lose()4.A.it B.thatC.themD.school bags()5.A.walked B.passed onC.passedD.walked by()6.A.taste B.smellC.soundD.feel()7.A.few B.someC.moreD.any()8.A.continued B.was doneC.beganD.was over()9.A.feel like B.look likeC.enjoyD.just like()10.A.love B.happinessC.friendshipD.hateⅠ. 阅读理解How can cactus(仙人掌) help the world? It can provide a new kind of sustainable fuel(可持续燃料). Nopalimex, a company in Mexico, has made one of the world’s first cactus-powered factories. The idea came to Sosa in Nopalimex when he was looking for ways to save money for his food factory. He now powers his factory with cactus gas(气体). The cost to produce the gas is half the cost of electricity.Soon, the gas produced by Nopalimex will also be used in cars. Nopalimex’s gas is made by using the prickly pear(刺梨)—a kind of cactus. To make the gas, the prickly pear is mixed together with manure(肥料). Then the mixture produces the gas that can be used as fuel.Why cactus? Fuel can be made from other plants such as corn, but there are a few reasons why cactus is a betterchoice. First, prickly pears need very little water and very little care, and grow well in hot temperatures. Today, these characteristics are key. Also, unlike corn, prickly pears don’t need space that could be used for other food plants. They can grow in areas where many food plants can’t grow. Last, after making gas from prickly pears and manure, their byproducts(副产品) can be used to help grow food.Scientists still need to do more research on making and using prickly pear gas. As projects like Nopalimex show, we have the possibility to produce more sustainable fuel to power our lives.1.How can cactus help the world?()A.By saving farmers’ money.B.By providing a new kind of sustainable fuel.C.By taking the place of corn.D.By producing a lot of electricity and gas.2.Why does Sosa power his factory with cactus gas?()A.Because he wants to save money for his food factory.B.Because he has grown a lot of cactus and corn in his town.C.Because he wants to be well-known around the world.D.Because he wants to grow cactus instead of corn.3.What does the underlined word “mixture” in Paragraph 2 refer to?()A.The Nopalimex company.B.The manure.C.The prickly pear and manure.D.Cactus.4.What is Paragraph 3 mainly about?()A.How cactus is used to produce gas.B.Where we can grow a lot of cactus.C.What Nopalimex does with cactus.D.Why cactus is a better choice to make fuel.Ⅰ. 选词填空阅读下列短文,用方框内所给单词的正确形式填空。
北师大版高一英语必修3_Unit9_30分钟限时训练题
Unit9 30分钟限时训练题Ⅰ.单项填空1．________ group wins on Saturday will go through to the world competition. A．No matter what B．No matter whichC．Whatever D．Whichever2．Children under six are not ________ to school except those of extraordinary intelligence.A．permitted B．accepted C．admitted D．received 3．Nowadays, too many children ________TV. That's bad for their eyesight and TV also keeps them from communicating with others.A．addicts to watchingB．are addicted to watchC．addict themselves to watchD．are addicted to watching4．My house is very ________ for getting to work as it is only a few minutes' walk from the station.A．comfortable B．suitable C．convenient D．available5．________ those who were not listening the first time, I will repeat the question. A．To the benefit of B．With the benefit ofC．For the benefit of D．With the benefit to6．The doctor had almost lost hope at one point, but the patient finally ________. A．pulled through B．pulled outC．pulled up D．pulled over7．—Do you think that housing price will keep ________ in the future?—Sorry, I have no idea.A．lifting up B．going upC．bringing up D．growing up8．________ your rotten idea, we went the long way.A．Thanks to B．Because C．Due to D．Since9．An earthquake struck this area，________ a lot of damage.A．making B．causing C．done D．caused10．The teacher proposed that Jack _____ maths or physics instead of English because he was quick at numbers.A．must study B．could studyC．studied D．studyⅡ.完形填空There are many different ways of seeing a town for the first time. One of them is to walk around it, a guidebook__11__hand. Of course, we may __12__ with our guidebooks the history and __13__ developments of a town and get to know them. __14__ then, if we take our time and __15__ in a town for a while, we may get to know it better. When we __16__it as a whole, we begin to have some __17__ ，which even the best guidebooks do not answer. Why is the town just __18__ this, this shape, this plan, this size? Why do its streets __19__in this particular way, and not in any __20__way?Here even the best guidebook__21__ us. One can't find in it the information about how a town has developed to the__22__ appearance. It may not describe the original (最初的) __23__ of a town. However, one may get some idea of what it__24__ look like by walking around the town. One can also imagine _25__the town was first planned and built. Then one can learn more about in what direction the town __26__ to develop.What is the __27__ of studying towns in this way? For me, it is __28__ that one gets a greater depth of pleasure by visiting and seeing a town with one's own eyes. A __29__ visit to a town may help one better understand why it is attractive __30__ just reading about it in a guidebook.11．A. in B．at C．by D．on12．A. write B．study C．tell D．remember13．A. strange B．similar C．separate D．special14．A. But B．Before C．Since D．Until15．A. march B．work C．stay D．wait16．A. look at B．look after C．look for D．look up17．A. ideas B．opinions C．feeling D．questions18．A. of B．for C．like D．as19．A. open B．run C．begin D．move20．A. one B．more C．other D．such21．A. helps B．tricks C．fails D．satisfies22．A. old B．normal C．first D．present23．A. capital B．meaning C．design D．change24．A. used to B．seemed to C．had to D．happened to25．A. what B．how C．when D．where26．A. stops B．appears C．starts D．continues27．A. point B．view C．problem D．difficulty28．A. nearly B．simply C．generally D．hardly29．A. costly B．formal C．group D．personal30．A. from B．than C．through D．withⅢ.阅读理解AIn 1885, a young doctor named Arthur Conan Doyle opened offices in London.He wanted to be a successful doctor, but for some reasons he never found enough patients. To pass the time, he began to write stories and send them to the newspapers.Conan Doyle's stories were about a clever detective, Sherlock Holmes. Conan Doyle wrote that Sherlock Holmes lived in Baker Street in London, and people with problems came to Sherlock Holmes with their problems, too. He was able to solve mysteries (疑难案件) that the cleverest policemen in England were unable to figure out.Sometimes Sherlock Holmes could solve a mystery without leaving his chair. He listened carefully to the information his client gave and figured out the answer. At other times he spent days or weeks looking for clues. Sherlock Holmes travelled to different cities and countries to solve the mysteries. Sometimes he wore disguises, pretending to be an old man, or a sailor. Holmes did anything to find out the answer to the mysteries he was working on.Sherlock Holmes is the most famous detective in English literature，but many people don't understand that he is a fictional character, not a real person. The English post offices report that people still send mail to Sherlock Holmes in Baker Street. Even he gets more than 2，000 letters every year.31．Conan Doyle began to write stories perhaps because ________．A．he wanted to tell something about his patientsB．he wasn't good at medicineC．he wanted to make less moneyD．most people were strong at that time32．Conan Doyle got to write very good detective stories because ________．A．many people asked him to solve their mysteriesB．he got a lot of experience in solving mysteriesC．he was a person with great literary quality and talentD．he was able to help those who came to see him with their problems 33．Sherlock Holmes________．A．was only an ordinary detectiveB．never existed in the worldC．was one of the members of the police in LondonD．was a real detective who was named by Conan Doyle34．The phrase “wore disguises” in the fourth paragraph means “ ________”．A．introduced oneselfB．was in old clothesC．changed one's clothes or one's appearanceD．seemed to be poor and helpless35．Instead of being a famous doctor，Arthur Conan Doyle came to be successful in writing because ________.A．many people wrote letters to him asking about the storiesB．the character he wrote about was thought to be a real personC．he was finally employed by a police stationD．he earned a lot of money by writing such a storyBA new study suggests that the round-the-clock(24小时的)availability that cell phones have brought to people's lives may be taking a toll on family life. The study，which followed more than 1，300 adults over 2 years, found that those whoconsistently used a mobile phone throughout the study period were more likely to r eport negative “spillover” between work and home life—and，in turn，less satisfaction with their family life.Spillover essentially(本质上)means that the line between work and home begins to become unclear. Work life may invade home life when a parent is taking job-related calls at home，for instance—or family issues may start to take up work time. For example，a child may call mum at work，telling her “microwave exploded”，explained Noelle Chesley，an assistant professor of sociology at the University of Wisconsin-Milwaukee and the author of the study. The problem with cell phones seems to be that they are allowing for even more spillover between work and home.This may be especially true for working women，the study found. Among men，consistent use of mobile phones seemed to allow more work issues to creep (潜入)into family time. But for women，the spillover tended to go in both directions. Being “connected” meant that work cut into home time，and family issues came into work life.Cell phones seem to be opening more lines for stressful exchanges among family members. But there may be ways to control the spillover，according to Chesley. Employers, she said，could look at their policies on contacting employees after hours to make sure their expectations are “reasonable”．For their part，employees could decide that cell phones go off during family time, Chesley said.36．What does the underlined phrase “taking a toll on” probably mean in Paragraph 1? A．Explaining. B．Founding. C．Damaging. D．Extending. 37．According to Chesley，what is the best solution to the problem caused by cell phones?A．Refuse to use cell phones.B．Separate work hours from family time.C．Ignore coming calls during family time.D．Encourage women to stay at home.38．We can learn from the passage that ________．A．cell phones make the line between work and home unclearB．cell phones seem to be convenient to familiesC．cell phones affect men as much as womenD．we can do nothing to solve the problem39．What is the main idea of the passage?A．How to control the negative spillover caused by cell phones.B．Cell phones cause negative “spillover” between work life and home life. C．Consistent use of cell phones makes people feel less satisfied with their work. D．How work life invades home life.参考答案及解析Ⅰ.1.D考查主语从句的引导词。
九年级英语限时训练(附参考答案)
九年级英语限时训练（附参考答案）（满分40分，时间30分钟）一.单词拼写（共5小题，每题2分，满分10分）根据句意和首字母或汉语提示，将单词的正确形式完整地写在横线上。
1. —Cindy, what kind of restaurants do you like ?—I p_____ restaurants that can provide customers with free Wi - Fi.2. Mr.King is very P ______. He often explains difficult problems many times until we understand.3. It’s_________（危险的）for people to use the mobile phone while crossing the street.4. China has been making many great _____（成就）in every field these years, which amazes the world.5. Teenagers should be_________（鼓励）to learn and spread Chinese traditional culture.二、综合填空（共10小题，每题2分，满分20分）根据短文内容，用方框中所给词语的适当形式填空，使文章通顺、完整。
（每词限用一次）hour, power, a, matter, pain, compete, good, point, keep, createEileen Gu was born in San Francisco, California to an American father and a Chinese mother. While 6._______ for the United States in her earlier years, Gu announced her decision to ski for China in 2019 after her first World Cup Italy. In the interview, Gu mentioned her 8.5 7.______training a day, which gives her the confidence to win.She scored 1,580 8. ________out of a maximum 1,600 in the SAT, the test used for college admissions in the United States. “I encourage you all to step out of your comfort zone to show the boys that girls are just as 9._________ as they are.” Gu said. “I’m not trying 10._________ anyone happy. I’m 11.________18-year-old girl living my best life. It doesn’t really12. _____ if other people are happy or not, because I feel I am doing my 13._______. I’m enjoying the entire process and I’m using my voice 14._______ as much positive change as I can, fo r the voice that will listen to me.”She’s not afraid of hardship, tiredness, and 15.______ .she’s especially positive and optimistic. she’s quite burning. A ball of flame was surrounding her.三、阅读理解（共5个小题，每题2分，满分10分）阅读下面的短文，从每题所给的A、B、C、D四个选项中，选出最佳答案。
2020新课标高考语文二轮总复习专题限时训练：2-8 名篇名句默写 Word版含解析
[课时训练]限时练(三十)1．补写出下列句子中的空缺部分。
(1)王湾《次北固山下》中，“______________，______________”两句写拂晓行船的情景，作者无意说理，却在描写景物、节令之中，蕴含着一种自然的理趣。
(2)杜牧《阿房宫赋》中“________________，________________，______________”连用整齐的短句，写秦朝统治者大肆挥霍从六国搜刮来的珍宝，极不珍惜。
【答案】(1)海日生残夜江春入旧年(2)鼎铛玉石金块珠砾弃掷逦迤2．补写出下列句子中的空缺部分。
(1)苏轼《赤壁赋》中，“__________________，__________________”两句生动形象地描绘出月亮在夜空中缓慢移动的状态，逼真传神。
(2)辛弃疾《永遇乐·京口北固亭怀古》中，写古代英雄叱咤风云、驰骋疆场的名句是“______________，________________”。
(3)《荀子·劝学》中，“_____________，_____________”两句强调了整天空想不如片刻学习收获大的道理。
【答案】(1)月出于东山之上徘徊于斗牛之间(2)金戈铁马气吞万里如虎(3)吾尝终日而思矣不如须臾之所学也3．补写出下列句子中的空缺部分。
(1)周敦颐在《爱莲说》中用“________________”和“________________”分别表达对菊花和牡丹的看法。
(2)李白在《蜀道难》中，用禽、兽都不能越过蜀道中的高山来侧面烘托蜀道之难的两句诗是“__________________，__________________”。
(3)在《赤壁赋》中，苏轼感觉自己“浩浩乎”“飘飘乎”的具体原因是作者与客在“水光接天”的环境下“________________，________________”。
【答案】(1)花之隐逸者也花之富贵者也(2)黄鹤之飞尚不得过猿猱欲度愁攀援(3)纵一苇之所如凌万顷之茫然4．补写出下列句子中的空缺部分。
2020中考英语30分钟限时训练 完形填空+还原短文+回答问题+词语运用 含答案
完形+还原短文+阅读填表格+词语运用(限时:30分钟)Ⅰ.[2019·乐山改编]完形填空A group of boys gathered around a tree. “What a tall tree!” they said to each other. “It would be 1 to climb to the top!”The group of boys then decided to play a game to see who could climb to the top of the tree 2 . Their mothers were sitting not far away, looking on at their children as they 3 . One of the climbers was an 8-year-old boy named David. He was the shortest child in the group. Nobody thought he would win the competition.Then the game started. All of the boys tried their best to climb as 4 as they could. Although they all made it halfway up the tree before David did, he reached the top of the tree fastest 5 . His mother was proud to see this. She asked him, “David, how did you 6 to reach the top of the tree so quickly?”“It was easy,” David said. “The other children kept looking down as they climbed. When they realized how high they were, they got scared(恐惧的) and were afraid of 7 down. I, however, looked only 8 . When I saw how close I was, I kept going higher and higher until I reached the top.”It is true in life that if we just keep going forward without looking back, we are more likely to reach our goals(目标).( )eful B.possible C.exciting( )st B.finally C.first( )3.A.studied B.played C.jumped( )4.A.high B.safely C.carefully( )5.A.as well B.in the end C.in time( )6.A.manage B.hope C.imagine( )7.A.looking B.climbing C.falling( )8.A.down B.up C.outⅡ.还原短文请阅读下面短文,根据短文内容,从方框内所给的选项中选出能填入空白处的最佳选项,使短文意思通顺。
高中数学必修4课后限时训练30 三角函数的积化和差、和差化积
高中数学必修4课后限时训练30 三角函数的积化和差、和差化积题组1：基础巩固一、选择题1．sin75°－sin15°的值为( )A ．12B ．22C ．32D ．－12 答案：B 解析：sin75°－sin 15＝2cos 75°＋15°2sin 75°－15°2＝2×22×12＝22.故选B. 2．已知cos(α＋β)cos(α－β)＝13，则cos 2α－sin 2β的值为( ) A ．－23 B ．－13C ．13D ．23答案：C解析：由已知得cos 2αcos 2β－sin 2αsin 2β＝13， ∴cos 2α(1－sin 2β)－sin 2αsin 2β＝13， 即cos 2α－sin 2β＝13. 3．化简cos α－cos3αsin3α－sin α的结果为( ) A ．tan α B ．tan2αC ．cot αD ．cot2α答案：B解析：原式＝－2sin2αsin (－α)2cos2αsin α＝2sin2αsin α2cos2αsin α＝tan2α.4．已知cos 2α－cos 2β＝m ，那么sin(α＋β)sin(α－β)等于( )A ．－mB ．mC ．－m 2D ．m 2答案：A解析：sin(α＋β)sin(α－β)＝(sin αcos β＋cos αsin β)(sin αcos β－cos αsin β)＝sin 2αcos 2β－cos 2αsin 2β＝(1－cos 2α)cos 2β－cos 2α(1－cos 2β)＝cos 2β－cos 2αcos 2β－cos 2α＋cos 2αcos 2β＝cos 2β－cos 2α＝－m .5．计算sin105°cos75°的值是( ) A ．12 B ．14C ．－14D ．－12 答案：B解析：sin105°cos75°＝12(sin180°＋sin30°)＝14.6．sin10°＋sin50°sin35°·sin55°＝( ) A ．14B ．12C ．2D ．4答案：B 解析：sin10°＋sin50°sin35°sin55°＝2sin30°cos20°－12(cos90°－cos20°) ＝14cos20°12cos20°＝12. 二、填空题7．在△ABC 中，已知sin B sin C ＝cos 2A 2，则此三角形是________三角形． 答案：等腰解析：sin B sin C ＝cos 2A 2＝1＋cos A 2， ∴2sin B sin C ＝1－cos(B ＋C )＝1－cos B cos C ＋sin B sin C ，∴cos B cos C ＋sin B sin C ＝1，即cos(B －C )＝1又－π<A <B <π，∴A －B ＝0，∴A ＝B .故△ABC 是等腰三角形．8．cos40°＋cos60°＋cos80°＋cos160°＝________.答案：12解析：原式＝cos40°＋cos80°＋cos60°－cos20°＝2cos60°·cos(－20°)＋cos60°－cos20°＝cos60°＝12. 三、解答题9．求证：sin(α＋β)cos α－12[sin(2α＋β)－sin β]＝sin β. 解析：解法一：左边＝sin(α＋β)cos α－12[sin 〔(α＋β)＋α〕－sin β] ＝sin(α＋β)cos α－12[sin(α＋β)cos α＋cos(α＋β)sin α]＋12sin β＝12[sin(α＋β)cos α－cos(α＋β)sin α]＋12sin β ＝12sin[(α＋β)－α]＋12sin β＝sin β＝右边． 解法二：左边＝sin(α＋β)cos α－12⎝ ⎛⎭⎪⎫2cos 2α＋β＋β2sin 2α＋β－β2 ＝sin(α＋β)cos α－cos(α＋β)sin α＝sin[(α＋β)－α]＝sin β＝右边．题组2：能力提升一、选择题1．已知sin(α－β)·cos α－cos(α－β)·sin α＝m ，且β为第三象限角，则cos β等于( )A ．1－m 2B ．－1－m 2C ．1＋m 2D ．－m 2－1答案：B解析：sin(α－β)cos α－cos(α－β)sin α＝sin(－β)＝－sin β，∴sin β＝－m .又β为第三象限角，∴cos β＝－1－m 2.2．若sin α＋sin β＝33(cos β－cos α)且α∈(0，π)，β∈(0，π)，则α－β等于( ) A ．－2π3 B ．－π3C ．π3D ．2π3 答案：D解析：∵α、β∈(0，π)，∴sin α＋sin β>0.∴cos β－cos α>0，∴cos β>cos α，又在(0，π)上，y ＝cos x 是减函数．∴β<α∴0<α－β<π，由原式可知：2sin α＋β2·cos α－β2＝33⎝ ⎛⎭⎪⎫－2sin α＋β2·sin β－α2， ∴tan α－β2＝3∴α－β2＝π3∴α－β＝2π3. 3．在△ABC 中，若B ＝30°，则cos A sin C 的取值范围是( )A ．[－1,1]B ．[－12，12] C ．[－14，34] D ．[－34，14] 答案：C解析：cos A sin C ＝12[sin(A ＋C )－sin(A －C )]＝14－12sin(A －C )，∵－1≤sin(A －C )≤1， ∴cos A sin C ∈⎣⎡⎦⎤－14，34. 4．tan70°cos10°(3tan20°－1)等于( )A ．1B ．－1C ．12D ．－12答案：B解析：原式＝cot20°cos10°(3tan20°－1) ＝cot20°cos10°3sin20°－cos20°cos20°＝cot20°cos10°2sin (20°－30°)cos20°＝－2sin10°cos10°cot20°cos20°＝－1. 二、填空题 5．sin 220°＋cos 280°＋3sin20°·cos80°＝________.答案：14 解析：原式＝1－cos40°2＋1＋cos160°2＋32sin100°－32sin60° ＝14－12cos40°－12cos20°＋32sin100° ＝14－12×2cos30°cos10°＋32cos10° ＝14－32cos10°＋32cos10°＝14.6．计算1tan10°－4cos10°＝________. 答案：3解析：1tan10°－4cos10°＝cos10°－2sin20°sin10°＝cos10°＋2sin (30°－10°)sin10°＝2cos30°sin10°sin10＝ 3. 三、解答题7．求函数y ＝sin 4x ＋23sin x cos x －cos 4x 的最小正周期和最小值；并写出该函数在[0，π]上的递增区间． 解析：y ＝sin 4x ＋23sin x cos x －cos 4x＝(sin 2x ＋cos 2x )(sin 2x －cos 2x )＋3sin2x＝3sin2x －cos2x ＝2sin ⎝⎛⎭⎫2x －π6. 故该函数的最小正周期是π；最小值是－2.递增区间为⎣⎡⎦⎤0，π3，⎣⎡⎦⎤56π，π. 8．在△ABC 中，求证：(1)sin 2A ＋sin 2B －sin 2C ＝2sin A sin B cos C ；(2)sin A ＋sin B －sin C ＝4sin A 2sin B 2cos C 2. 解析：(1)左边＝sin 2A ＋1－cos2B 2－1－cos2C 2＝sin 2A ＋12(cos2C －cos2B ) ＝sin 2(B ＋C )＋sin(B ＋C )sin(B －C )＝sin(B ＋C )[sin(B ＋C )＋sin(B －C )]＝sin(B ＋C )2sin B cos C ＝2sin A sin B cos C ＝右边， ∴等式成立．(2)左边＝sin(B ＋C )＋2sin B －C 2cos B ＋C 2＝2sin B ＋C 2cos B ＋C 2＋2sin B －C 2cos B ＋C 2＝2cos B ＋C 2⎝ ⎛⎭⎪⎫sin B ＋C 2＋sin B －C 2 ＝4sin A 2sin B 2cos C 2＝右边，∴原等式成立． 9．讨论函数f (x )＝12cos(2x －2α)＋cos 2α－2cos(x －α)·cos x ·cos α的周期、最值、奇偶性及单调区间． 解析：f (x )＝12cos(2x －2α)＋1＋cos2α2－2cos(x －α)cos x ·cos α ＝12＋12[cos(2x －2α)＋cos2α]－[2cos(x －α)·cos α]cos x ＝12＋cos x ·cos(x －2α)－cos x [cos x ＋cos(x －2α)] ＝12－cos 2x ＝12－1＋cos2x 2＝－12cos2x . ∴函数的最小正周期T ＝2π2＝π. f (x )max ＝12，此时cos2x ＝－1，即2x ＝2k π＋π，k ∈Z ，x ＝k π＋π2，k ∈Z ； f (x )min ＝－12，此时cos2x ＝1， 即2x ＝2k π，k ∈Z ，x ＝k π，k ∈Z .f (－x )＝f (x )，∴f (x )为偶函数．由2k π≤2x ≤2k π＋π，k ∈Z ，即k π≤x ≤k π＋π2，k ∈Z . ∴函数f (x )的增区间为[k π，k π＋π2](k ∈Z )． 由2k π＋π≤2x ≤2k π＋2π，k ∈Z ，即k π＋π2≤x ≤k π＋π，k ∈Z . ∴函数f (x )的单调减区间为[k π＋π2，k π＋π]，k ∈Z .。
2020中考英语30分钟限时训练 完形+还原短文+阅读填表格+词语运用 附答案
完形+还原短文+阅读填表格+词语运用(限时:30分钟)Ⅰ.[2019·呼和浩特改编]完形填空“The grass looks greener on the other side of the fence.” That's an old 1 in English. It means other places often look better, more interesting than the place in 2 you live. Some people worry 3 young Chinese are beginning to feel that way. They see young Chinese paying no attention to Chinese culture and, 4 , buying Japanese cartoon books, watching Korean soap operas and even celebrating Western holidays.Foreign books and soap operas are good, 5 Chinese writers and actors are just as good. As for holidays, Christmas is nice, but it can 6 have the meaning for Chinese that the Spring Festival has, and the West has nothing to compare with the Mid-autumn Festival. And let's not forget the part of Chinese culture I like best—its friendliness. Not all countries are as 7 as China.It's good to enjoy other cultures and to learn from them, but they cannot replace your own culture. It's good to look on the other side of the fence,but 8 you take a good long look. You will find that the grass isn't always greener on the other side of the fence.( )1.A.word B.saying C.sentence( )2.A.that B.when C.which( )3.A.that B.if C.why( )4.A.however B.besides C.instead( )5.A.and B.so C.but( )6.A.still B.never C.always( )7.A.warm B.hot C.cold( )8.A.make up B.make up of C.make sureⅡ.[2019·威海改编]还原短文请阅读下面短文,根据短文内容,从方框内所给的选项中选出能填入空白处的最佳选项,使短文意思通顺。
立体几何初步(限时训练30’)答案
1. A2. D3. B【解析】若任取三点都共线，则有 4 个点都共线，与题设不符4. D【解析】这个几何体为如图所示的直三棱锥，高为 1．∴ V =61. 5. D 6. 32321S S S ．【解析】设三条侧棱长分别为 a ，b ，c ，则 21ab = S 1，21bc = S 2，21ca = S 3． 三式相乘，得81a 2 b 2 c 2 = S 1S 2S 3． ∴ abc = 23212S S S ．∵ 三侧棱两两垂直，∴ V =31(21ab )·c =31abc ·21 =313212S S S ．7. 证明：连接D 1E ，D 1F ，并分别延长，使D 1F 与DC 的延长线交于点H ，D 1E 的延长线与DA 的延长线交于点G ．∵ D 1，E ，F 三点不共线，∴ D 1，E ，F 确定一个平面 ．∴ G ，H ∈α．又∵点 E 是AA 1的中点，∴EA 21DD 1，∴ 点 A 是DG 的中点． 同理可得，点 C 是DH 的中点．∴ CH = BC = BA = GA ． 又∵ 四边形 ABCD 是正方形，∴ ∠BCH =∠BAG = 90°．连接BH ，BG ．∴ △BCH ，△GAB 是全等的等腰直角三角形． ∴ ∠CBH =∠ABG = 45°．∴ ∠GBA +∠ABC+∠CBH = 180°． ∴ G ，B ，H 三点共线．又G ，H ∈α，∴ GH ⊂α，而B ∈GH ，∴ B ∈α．∴ D 1，E ，F ，B 四点共面．2. 证明：∵ α∩β= a ，α∩γ= b ，∴ a ⊂ β，b ⊂γ．又∵ a ∩b = O ，∴ O ∈a ，O ∈b ．∴ O ∈β，O ∈γ． ∴ 点 O 在 β，γ的交线 c 上．∴ 三条直线 a ，b ，c 相交于点 O ．8. 证明：取PD 的中点为Q ，连接AQ ，QN ， ∵ 点 N 为PC 的中点，∴ QN 21DC ， A M BCND Q P∴QN AM，∴四边形AMNQ为平行四边形，∴MN∥AQ，∴MN∥平面P AD．。
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O
x
x+y-3=0
x=1
6.解析该几何体的直视图如图所示，取 AB 的中点 C ，连接 CD, PC ，
PC
2
2
PD CD
22
2
3 7
1
1
S△PAB AB PC 2 7 7 .故选 A.
2
2
1
7.解析 函数 f x 的图像如图所示，若方程 f x a 有三个不同的实数根，则实数 a 的取值范围为 0,1 .故选 D.
题，使解答变得易于操作.
3
1
1
点 P 的轨迹的周长为 l△MFE 2 l△SDB 2 2 2 3 3 2 3 .故选 B.
S
M
D
F
C
E
A
B
二、填空题
9.解析解法一：因为 sin
1 2
，且
π 2
,π
，所以
5π 6Leabharlann ， 25π 3
，
5π 所以 tan 2 tan 3 .
50
公式可得 d
1.故选 C.
5
x2 y2
评注
双曲线
a2
b2
1a 0,b 0 的一个焦点到其渐近线的距离（渐焦距）为 b ，做选填题时可直
接利用此结论得出结果.
4. 解析 2 cos 0, 即 cos 1 0 ，所以 0 ，或 cos 1 .化为直角坐标系即为
限时训练（三十）
答案部分
一、 选择题
1
2
3
4
5
6
7
8
B
D
C
C
B
A
D
B
二、 填空题
9. 3
23
10.
3
11. 40
12.10
解析部分
13.1 14. ②③
一、选择题
1. 解析 1 2i a i a i 2ai 2i2 a 2 1 2ai 为纯虚数，
14.解析① y' = 3x2 1, f x 1 有两个相等实根，因此曲线 y x3 x 不具有“可平行性”；
1
1
② y' 1 x2 ，f x a
a ,1
总有两个不同的实根与之对应，因此曲线 y x 是具有“可 x
平行性”的曲线；
③ y' cos x ，则 cos x a a 1,1 至少有两个不同的实根与之对应，因此曲线 y sin x 是具有“可
OE 1 OB 1 OD ，所以 DOC 60 ， C 30 .又 CD 2 ，所以 OD 2
3
4
， OC
3
，
22
3
3
2
23 BC OC OB .
3
D
A
O EB
C
11.解析 依题意，从 6 个数字中任取 3 个，然后将这 3 个数字中最大的数字做为十位数字，其余两个再
平行性”的曲线；
1
④ y' = 2x + 4 ，当 f x 2 2 4 时，只有一个实根 x
2
2
，因此曲线 x 2 ln x 不具有“可
x
2
平行性”.
综上，②③是具有“可平行性”的曲线.
评注 本题将“可平行性”这一抽象的概念转化为曲线对应函数的导函数是否存在 2 个不同的零点的问
3
1
π
3
3
解法二：因为 sin
2
，且
2
,π
，所以 cos
2
, tan
3
.
3
2
2 tan
则 tan 2
3 3.
1 tan2
2
3
1
3
10.解析如图所示，连接 OD ，如图所示.因为 D 为切点，所以 OD CD ，因为 E 为 OB 中点，所以
则 a 2 0 ， a 2 .故选 B.
2. 解析解1 x 0 ，得 x 1，即 M x x 1 ，所以 R M x x 1 .故选 D.
3. 解析由双曲线的对称性，不妨求双曲线的右焦点 5, 0 到渐近线 x 2 y 0 的距离.由点到直线距离
x2 y2 0 ，或 x 1 .故选 C.
5.解析如图所示，由约束条件作出可行域如图所示，
要使得 tan AOB 最大，则 AOB 取最大，
即 A 1, 2 ， B 2,1 为所求，此时
1
tan AOB
2 2
3 . 故选 B.
1 1 2
4
2
y
A B
x-3y+1=0
排列，所以“组合数”有
C36
A
2 2
40 个.
12.解析 2a3 a2a4 a32 ， a3 0 ，所以 a3 2 .又 b3 a3 ，所以 b3 2 .因为数列bn 为等差数列，所
以 S5 5b3 5 2 10 .
13.解析 由已知 f 1 0 ，所以 f f 1 f 0 0 a 3t2dt a3 1，解得 a 1. 0
8. 分析 PE AC 0 ，过 E 作与 AC 垂直的平面，设该平面截四棱锥所得的图形即为动点 P 的轨迹.
解析 如图所示，取 SC ，DC 的中点 M ，F ，则 EF //BD ，ME//SB ，所以平面 SBD// 平面 MEF ，
而 AC 平面 SBD ，所以 AC 平面 MEF ，则动点 P 在四棱锥表面上运动的轨迹为△ MEF ，则动