28043chap4--chap8分章练习
计算机网络课后习题参考答案第四章
第四章网络层1.网络层向上提供的服务有哪两种？是比较其优缺点。
网络层向运输层提供“面向连接”虚电路（Virtual Circuit）服务或“无连接”数据报服务前者预约了双方通信所需的一切网络资源。
优点是能提供服务质量的承诺。
即所传送的分组不出错、丢失、重复和失序（不按序列到达终点），也保证分组传送的时限，缺点是路由器复杂，网络成本高；后者无网络资源障碍，尽力而为，优缺点与前者互易2.网络互连有何实际意义？进行网络互连时，有哪些共同的问题需要解决？网络互联可扩大用户共享资源范围和更大的通信区域进行网络互连时，需要解决共同的问题有：不同的寻址方案不同的最大分组长度不同的网络接入机制不同的超时控制不同的差错恢复方法不同的状态报告方法不同的路由选择技术不同的用户接入控制不同的服务（面向连接服务和无连接服务）不同的管理与控制方式3.作为中间设备，转发器、网桥、路由器和网关有何区别？中间设备又称为中间系统或中继(relay)系统。
物理层中继系统：转发器(repeater)。
数据链路层中继系统：网桥或桥接器(bridge)。
网络层中继系统：路由器(router)。
网桥和路由器的混合物：桥路器(brouter)。
网络层以上的中继系统：网关(gateway)。
4.试简单说明下列协议的作用：IP、ARP、RARP和ICMP。
IP协议：实现网络互连。
使参与互连的性能各异的网络从用户看起来好像是一个统一的网络。
网际协议IP是TCP/IP体系中两个最主要的协议之一，与IP协议配套使用的还有四个协议。
ARP协议：是解决同一个局域网上的主机或路由器的IP地址和硬件地址的映射问题。
RARP：是解决同一个局域网上的主机或路由器的硬件地址和IP地址的映射问题。
ICMP：提供差错报告和询问报文，以提高IP数据交付成功的机会因特网组管理协议IGMP：用于探寻、转发本局域网内的组成员关系。
5.IP地址分为几类？各如何表示？IP地址的主要特点是什么？分为ABCDE 5类;每一类地址都由两个固定长度的字段组成，其中一个字段是网络号net-id，它标志主机（或路由器）所连接到的网络，而另一个字段则是主机号host-id，它标志该主机（或路由器）。
数据库系统基础教程课后答案第四章
4.2.7 In below figure there exists a many-to-one relationship between Babies and Births and another many-to-one relationship between Births and Mothers. From transitivity of relationships, there is a many-to-one relationship between Babies and Mothers. Hence a baby has a unique mother while a birth can allow more than one baby.
4.1.7
4.1.8 a)
(b)
4.1.9
Assumptions A Professor only works in at most one department. A course has at most one TA. A course is only taught by one professor and offered by one department. Students and professors have been assigned unique email ids. A course is uniquely identified by the course no, section no, and semester (e.g. cs157-3 spring 09).
4.2.4 The entity sets should have single attribute. a) Stars: starName b) Movies: movieName c) Studios: studioName. However there exists a many-to-many relationship between Studios and Contracts. Hence, in addition, we need more information about studios involved. If a contract always involves two studios, two attributes such as producingStudio and starStudio can replace the Studios entity set. If a contact can be associated with at most five studios, it may be possible to replace the Studios entity set by five attributes viz. studio1, studio2, studio3, studio4, and studio5. Alternately, a composite attribute containing concatenation of all studio names in a contact can be considered. A separator character such as "$" can be used. SQL allows searching of such an attribute using query like '%keyword%'
国际金融练习ch04
国际⾦融练习ch04Chapter 4:The Forward Currency Market and International Financial Arbitrage I. Chapter OverviewChapter 4 studies the forward currency market and its role in providing investors with opportunities to hedge against foreign currency exchange risk. The chapter begins with a discussion of the various types of risk to which companies engaging in foreign currency transactions expose themselves, and distinguishes among three types of exposure: (1) transaction exposure, which is the risk that the costs or proceeds from a transaction will change in value, (2) translation exposure, which is the risk that the value of assets and liabilities will change when translated to a single currency value, and (3) economic exposure, which is the risk that a firm's present value stream of future income will change as a consequence of exchange rate changes. In the second section, a forward exchange contract is motivated as a means by which agents can cover themselves against these risks. The section ends with a discussion of the extent to which forward exchange rates are good predictors of future spot rates, and concludes that in practice they are not very good predictors.The third section of the chapter covers international financial arbitrage. It presents a supply and demand model for the loanable funds market and shows how the equilibrium market interest rate is determined. Next it demonstrates that when expected returns on two different instruments are the same, it is implied that the real interest rates should equalize between the two, and presents this as interest parity. If interest parity exists between the instruments of different national currencies, then no net flow of funds should occur between the two. But when the instruments are denominated in two different national currencies, then this implies that there will also be exchange risk. If investors cover these exchange risks by using the forward exchange market, we then have the covered interest parity condition.The fourth section introduces uncovered interest parity, which is described as a condition in which investors do not use the forward market to hedge against foreign exchange risk. In this case, the extent to which future exchange rate changes do not compensate for interest rate differentials on the instruments denominated in the two different national currencies reflects the presence of a risk premium. This risk premium may reflect risks other than exchange risk, such as country risk stemming from country specific political or fiscal uncertainties. The next section points out that when both covered and uncovered interest parity hold, then this implies that the forward premium will be equal to the expected change in the spot rate, a condition which is also taken as indicative of foreign exchange market efficiency. The last section of the chapter provides a discussion of Eurocurrency markets and the extent to which these can play a similar role as the forward exchange market in that they allow investors to avoid foreign exchange risk.II. OutlineA. Foreign Exchange Risk1. Types of Foreign Exchange Risk Exposure2. Hedging Foreign Exchange RiskB. The Forward Exchange Market1. Covering a Transaction with a Forward Contract2. Determination of Forward Exchange Rates3. The Forward Exchange Rate as a Predictor of the Future Spot RateC. International Financial Arbitrage1. The International Flow of Funds and Interest Rate Determinationa. Supplyb. Demandc. Determination of the Market Interest Rate2. Interest Parity3. Exchange Uncertainty and Covered Interest Paritya. Covered Interest Arbitrageb. Covered Interest Parity Gridc. Covered Interest Arbitrage and Savings Flowd. Adjustment to an EquilibriumD. Uncovered Interest Parity1. Uncovered Interest Arbitrage2. Risk and Uncovered Interest Parity3. Risks Other than Foreign Exchange Risk4. Tests of Uncovered Interest ParityE. Foreign Exchange Market Efficiency1. Market Efficiency2. Evidence on Foreign Exchange Market EfficiencyF. International Financial Markets1. International Capital Markets2. International Money Markets3. Eurobonds, Euronotes, and Eurocommercial Paper4. Eurocurrenciesa. Origins of the Eurocurrency Marketb. Relationship to the Forward MarketG. Chapter SummaryIII. F undamental Issues1. What is foreign exchange risk?2. What is the forward currency market, and how are forward exchange rates determined?3. What is covered interest parity?4. What is uncovered interest parity?5. What is foreign exchange market efficiency?6. What are the international financial markets?IV. Chapter Features1. Management Notebook: Exchange rate Risk and the Annual Report of BallCorporationThe management notebook uses statements from the annual report of Ball Corporation, one of the world’s largest food and beverage packaging manufactures, to illustrate the translation exposure of a firm that operates in various foreign currencies. The feature also references the Financial Accounting Standards Board’s (FASB) standards fo r translating foreign-currency denominated assets and liabilities.For Critical Analysis: During a period in which the U.S. dollar is expected to depreciate, Ball Corporation, a U.S. based company could protect itself from foreign-exchange risk by selling a currency forward on long positions and buying a currency forward on short positions.2. Online Notebook: Policy Transparency via the InternetThis online notebook discusses the International Monetary Fund’s Code of Good Financial Practices on Transparency in Monetary and Financial Policies. Following the IMF’s recommendations, most central banks now post important economic information and data on their own Web sites. The “code” is described on the IMF’s website at . The Bank for International Settlements keeps a list of quick links to most central bank Web sites at .For Critical Analysis: Data availability can affect perceptions of risks in two ways. On the one hand, a greater amount of information reduces uncertainty and can, therefore, improve perceptions of risk. On the other hand, if the information is bad, say that a central bank is running out of foreign exchange reserves in an attempt to maintain an exchange rate peg, the information can heighten perceptions of risk.V. Answers to End of Chapter Questions1. Given that the exchange rate is expressed as dollars to euros, we treat the dollar as the domestic currency. Note also that interest rates are quoted on an annual basis eventhough the maturity period is only one month. In this problem we divide the interest rates by 12 to put them on a one-month basis.a. The interest rate differential, therefore, is (1.75%/12 - 3.25%/12) = -0.125%. Theforward premium/discount, expressed as a percentage, is calculated as:((F-S)/S)?100 = ((1.089 – 1.072)/1.072)?100=1.5858%b. Transaction costs are shown in the figure above by the dashed lines that interest the horizontal axis at values of -1.00 and1.00.c. The positive value indicates that the euro is selling at a premium. In addition, the interest rate differential favors the euro-denominated instrument. Hence, a saver shift funds to euro-denominated instruments.2. Using the provided information:(1.75/12) – (3.25/12) < [(1.089 - 1.072/1.072)]?100-0.125% < 1.5858%.3. The four markets are graphed below. An explanation follows.Graph 1, the spot market for the euro.R – R*45(F-S)/S-0.125 1.58581.00-1.00 $/€Graph 2, the forward market for the euro.Graph 4, U.S. loanable fundsGraph 5, Euro loanable fundsIn graph 1, the demand for the euro rises as international savers shift funds into euro-denominated instruments. In graph 2, the supply of euros increases in the forward market. (Consider a U.S. saver that moves funds into a euro-denominated instrument. They would desire to sell the euro forward so they may convert euro-denominated proceeds at the time of maturity into their dollar equivalent.) Graph 3 illustrates a decrease inloanable funds in the United States as savers shift funds to euro-denominated instruments. Graph 4 illustrates the increase in the supply of loanable funds that occurs when savers shift funds to the euro-denominated instrument.$/€4. Because (1.03125) > (1.04250)(1.4575/1.5245) = 0.9967, an arbitrage opportunityexists in this example if one were to borrow the pound and lend the euro. Suppose you were to borrow one pound, the steps are then:a. Borrow ￡1, convert to €1.5245 on the spot market.b. Lend euros, yielding €1.5245?(1.03125) = €1.5721.c. See euros forward, yielding €1.5721/1.4575 = ￡1.0787.d. Repay the pound loan at ￡1?(1.04250) = ￡1.04250.e. The profit is ￡0.0362, or 3.62 percent.5. Because interest rates are quoted as annualized rates, we need to divide each interestrate by 4 (12/3). The uncovered interest parity equation is:R -R* = (S e+1 - S) /Sa. Rewriting the equation for the expected future expected exchange rate yields:S e+1 = [(R- R*) + 1]Sb. Using the values given yields the expected future spot rateS e+1 = [(0.0124/4 - 0.0366/4) + 1]?1.5245 = 1.5153.6. Given this information, we can calculate the forward premium/discount with the UIPcondition:(F - S)/S = R - R*The interest differential is 1.75% - 3.25% = 1.5%. This is the expected forwardpremium on the euro. Hence, (F – 1.08)/1.08 = 0.015 implies that F = 1.0962.7. We can adjust for the shorter maturity by dividing the interest rates by 2 (12/6). Nowthe interest differential is 0.75%, still a forward premium on the euro. The forward rate now is (F – 1.08)/1.08 = 0.0075 implies that F = 1.0881.8. The U.S. real rate is 1.24% – 2.1% = -0.86% and the Canadian real rate is 2.15% –2.6% = -0.45%. Ignoring transaction costs, because the real interest rates are notequal, real interest parity does not hold.9. Uncovered interest parity is R -R* = (S e+1 - S) /S + ρ.a. Using the same process as in question 5 above, the expected future spot rate is:S e+1 = [(R- R*) + 1]S,S e+1 = [(0.075 - 0.035) + 1]?30.35 = 31.564.b. Using the same process as in question 5 above, the expected future spot rate is:S e+1 = [(R- R*) + 1 - ρ]S,S e+1 = [(0.075 - 0.035) + 1 –0.02]?30.35 = 30.957.10. Because the forward rate, 30.01, is less than the expected future spot rate, 30.957, youshould sell the koruna forward. For example, $1 would purcase k30.957, which you could sell forward yielding k30.957/30.01 = $1.0316.11. International financial instruments:a. Global Bond: long term instruments issued in the domestic currency.b. Eurobond: term is longer than one year and is issued in a foreign currency.c. Eurocurrency: keyword is that it is a deposit.d. Global equity: keyword is that it is a share.VI. Multiple Choice Questions1. Your Canadian-based firm expects to receive a euro-payment in 30 days. Your firm is:A. short the Canadian dollar.B. long the Canadian dollar.C. short the euro.D. long the euro.Answer: D2. Your Canadian-based firm expects to receive a euro-payment in 30 days. This is an example of:A. covered arbitrage.B. transaction exposure.C. translation exposure.D. risk premium.Answer: B3. The act of offsetting exposure to risk is known asA. dodging.B. hedging.C. speculating.D. avoidance.Answer: B4. A covered exposure is oneA. that is backed by the government.B. in which exposure to foreign exchange risk is offset.C. that is established via foreign direct investment.D. that is impossible in most bond markets.Answer: B5. A market in which contracts for a future delivery of a foreign currency are established is:A. the S&P 500.B. the spot exchange market.C. the forward exchange market.D. global capital market.Answer: C6. A short position in a foreign currency implies that the investorA. will deliver the foreign currency in the future.B. will receive the foreign currency in the future.C. has an economic exposure.D. has a translation exposure.Answer: A7. If the forward exchange rate, defined as the domestic currency price of the foreign currency, is greater than the spot exchange rate there is a:A. forward premium on the foreign currency.B. forward discount on the foreign currency.C. shortage of dollars.D. surplus of dollars.Answer: A8. If the foreign currency is selling at a forward discount, then according to the efficientmarkets hypothesis one wouldA. a depreciation of the currency.B. an appreciation of the currency.C. a devaluation of the currency.D. a revaluation of the currency.Answer: A9. The forward premium has proved to beA. a stable predictor of the future spot rate.B. a near-perfect predictor of future spot rates.C. a biased predictor of future spot rates.D. of no help in predicting future spot rates.Answer: C10. The existence of unexploited profit opportunities is referred to asA. the parity condition.B. equilibrium.C. interest rate parity.D. an arbitrage opportunity.Answer: D11. Interest rate equalization across countries on similar financial instruments is calledA. sterilization.B. optimization.C. interest rate parity.D. an arbitrage opportunity.Answer: C12. Covered interest rate parity implies that the difference between the domestic and foreign interest rates should equalA. zero.B. the forward premium or discount.C. the purchasing power parity exchange rate.D. the yield to maturity.Answer: B13. One limitation of using forward markets as a hedge isA. that a sizable minimum transaction is required in order to participate in forward markets.B. an insufficient number of speculators who are willing to absorb the riskiness ofthe transaction.C. an absence of government regulation in forward markets.D. that forward markets are exchange tradable.Answer: A14. The condition relating interest differentials to an expected change in the spot rate ofthe domestic currency is calledA. covered interest rate parity.B. uncovered interest rate parity.C. absolute purchasing power parity.D. relative purchasing power parity.Answer: B15. Uncovered interest rate parity may not hold exactly due toA. a risk premium.B. a hedge adjustment.C. the inflation effect.D. an adjustment for nominal rather than real interest rates.Answer: A16. The additional risk of a currency due to political instability is referred to asA. anarchy.B. the discount factor.C. unhedgeable.D. country risk.Answer: D17. If market participants could forecast perfectly, then one would expect theA. forward premium to be equal to the difference between the future spot rate andthe current spot rate, divided by the current spot rate.B. current spot rate to be equal to the future spot rate minus the current spot rate.C. forward premium to be equal to the future spot rate.D. forward premium to be equal to the current spot rate.Answer: A18. Suppose that a currency speculator notes that the 90-day forward rate on the euro is $1.10/€. Suppose further that the speculator believes that in 90 days the spot rate will be $1.20/€. If this is the case, the speculator should do which of the following to earn a profit?A. Buy U.S. dollars on the forward market.B. Sell euros on the forward market.C. Buy euros on the forward market.D. Sell U.S. dollars in the spot market.Answer: C19. In which of the following situations, given that exchange rates are defined asdomestic currency units to foreign currency units, would a speculator wish to sell foreign currency on the forward market?A. If S e+1 < FB. If S e+1 > FC. If S e+1 = FD. If S e+1 = 1/FAnswer: A20. In which of the following situations would a speculator wish to purchase foreigncurrency on the forward market?A. If S e+1 < FB. If S e+1 > FC. If S e+1 = FD. If S e+1 = 1/FAnswer: B21. A market where prices adjust quickly to new and relevant information is calledA. stable.B. opaque.C. rational.D. efficient.Answer: D22. The most likely reason why the forward rate actually does a poor job of forecastingthe future spot exchange rate is theA. presence of irrational expectations.B. presence of a variable risk premium.C. unpredictability of interest rates.D. notoriously inaccurate nature of the data on forward rates.Answer: B23. A bank deposit denominated in a currency other than that of the nation in which thebank deposit is located is referred to as a(n):A. ADR.B. reciprocal transfer.C. Eurocurrency.D. Eurobond.Answer: C24. One theory of the of the origin of the Eurocurrency markets has to do with theA. development of a black market for illegally obtained funds.B. former Soviet Union moving U.S. assets to Europeans banks for security reasons.C. U.S. lending to European allies during WWII.D. former Soviet Union selling off its reserves of U.S. dollars.Answer: B25. The most heavily traded currency on the Eurocurrency market is theA. British pound.B. Canadian dollar.C. Japanese yen.D. U.S. dollar.Answer: D26. Covered interest arbitrage in the eurocurrency markets isA. often profitable due to the avoidance of country risk.B. often profitable due to differing tax treatments on assets held outside of the country.C. seldom profitable due to equilibrium conditions with forward markets.D. seldom profitable due to investor indifference.Answer: C27. The uncovered interest rate parity is a condition regardingA. nominal interest rates and future spot exchange rates.B. real interest rates and future spot exchange rates.C. nominal interest rates and current spot exchange rates.D. real interest rates and current spot exchange rates.Answer: A。
TCPIP协议族4-9131415章答案
TCPIP协议族4-9131415章答案第4章IP地址：分类编址8.试把以下的IP 地址从二进制记法转换为点分十进制记法。
a.0 1111111 11110000 01100111 11111101b.10101111 11000000 11110000 00011101c.11011111 10110000 00011111 01011101d.11101111 11110111 11000111 00011101e.11110111 11110011 10000111 11011101解我们把每一组8 位换成其等效十进制数，并增加隔开的点：a.127.240.103.253b.175.192.240.29c.223.176.31.93d.239.247.199.29e.247.243.135.22111.试找出以下IP 地址的netid 和hostid：a.114.34.2.8b.19.34.21.5c.23.67.12.1d.127.23.4.0解以上IP 地址都是 A 类地址，故前8 位为netid，后24 位为hostid解a.创建500 个子网，这表示我们应当在这个场所的前缀上增加9 个1（log 5002 9），子网前缀是/17，所以子网掩码是：255.255.128.0.b.每一个子网有232 17215个地址.c.第一个子网的第一个地址是：16.0.0.0/17，最后一个地址是：16.0.127.255/17.前缀长度是17，这表示我们必须保留前17 位不变，然后把剩下的15 位置为0，所以第一个地址是16.0.0.0/17；为了找出最后一个地址，我们需要把232 17215 -1 （用点分十进制表示为127.255）与第一个地址相加，得到结果16.0.127.255/17.d.最后一个子网的第一个地址是：16.249.128.0/17，最后一个地址是：16.249.255.255/17.由于要500 个子网，而前缀长度是17，其网络号要加上500-1=499 为16.00000000.0| 0000000.016.11111001.1 |0000000.0………………………………16.249.128.06.某组织分配到地址块130.56.0.0/16。
计算机第7、8章习题
第7、8章练习题1. 单选题1．计算机网络的目标是实现______。
A）数据处理B）文件检索C）资源共享和数据传输D）信息传输2．在计算机网络中，通常把提供并管理共享资源的计算机称为______。
A）服务器B）工作站C）网关D）网桥3．Internet中的IP地址由四个字节组成，每个字节间用______符号分隔开。
A）。
B），C）；D）.4．将计算机网络分为星型、环型、总线型、树型和网状型等是按______分类的方法。
A）传输技术B）交换方式C）拓扑结构D）覆盖范围5．个人用户通过PPP/SLIP接入Internet时，用户需要准备的条件是：一个Modem，一条电话线，PPP/SLIP软件与______。
A）网卡B）向Internet网络服务提供商（ISP）或校园网网管中心申请一个用户账号C）TCP/IP协议D）IP地址6．一个URL地址为ftp://，则这个URL地址中使用的协议是_____。
A）FTP B）TelnetC）HTTP D）Gopher7．计算机网络中，可以共享的资源是指_____。
A）硬件和软件B）硬件、软件和数据C）外设和数据D）软件和数据8．最早在美国出现的计算机网络是______。
A）Novell B）ARPANETC）Internet D）LAN9．网络标准100BASE-T中的100是指______。
A）100Mbit/s B）100MHzC）100米D）100个节点10．下列关于用户使用电话线连接Internet的说法中，正确的是_____。
A）只能使用脉冲电话B）只能使用音频电话C）脉冲、音频电话都能使用D）脉冲电话无须使用Modem11．拨号接入Internet需要一些条件，以下各项中，_____不是必要的条件。
A）电话线B）ISP提供的电话号码C）调制解调器D）IE浏览器12．IP地址的长度为_____位二进制数。
A）16 B）24C）32 D）4813．Internet是全球互联网络，通过_____协议将不同类型的网络和计算机连接起来。
网络协议分析题库
第一章练习1 OSI和ISO分别代表什么含义？它们是什么关系？2 OSI/RM模型没有被最终采用的原因是什么？3下面哪些协议属于应用层协议？（）A. TCP和UDPB. DNS和FTPC. IPD. ARP4 Internet最早是在( ) 网络的基础上发展起来的?A. ANSNETB. NSFNETC. ARPANETD. MILNET5 当网络A上的主机向网络B上的主机发送报文时, 路由器要检查( ) 地址?A.端口B. IPC.物理D.上述都不是6.下面哪一个是应用层提供的服务? ( )A.远程登录服务B.文件传送C.邮件服务D.上述都是7要将报文交付到主机上的正确的应用程序, 必须使用( )地址?A.端口B. IPC.物理D.上述都不是8. 网络应用访问操作系统的常用接口是,实现IP地址到物理地址映射的协议是。
9. 在TCP/IP协议族中，能够屏蔽底层物理网络的差异，向上提供一致性服务的协议是；实现异构网络互联的核心设备是。
10. 在TCP/IP网络中，UDP协议工作在层，DNS协议工作在层。
11判断对错：TCP/IP是一个被广泛采用的网际互联协议标准，仅包含TCP和IP两个协议。
（）第二章练习1 PPP协议是什么英文的缩写？用于什么场合?2 ISP验证拨号上网用户身份时,可以使用哪些认证协议？3.PPP协议的通信过程包括哪几个阶段？4.LCP的用途是什么?5.PPP是Internet中使用的（1），其功能对应于OSI参考模型的（2），它使用（3）技术来解决标志字段值出现在信息字段的问题。
（1）A. 报文控制协议 B. 分组控制协议C. 点到点协议D. 高级数据链路控制协议（2）A. 数据链路层 B. 网络层 C. 传输层 D. 应用层（3）A. 透明传输 B. 帧 C. 控制 D. 字节填充第三章练习1求下列每个地址的类别：227.12.14.87 193.14.56.22 14.23.120.8 252.5.15.1112 假设一段地址的首地址为146.102.29.0，末地址为146.102.32.255，求这个地址段的地址数。
计算机基础习题第四章
第四章一、单选1.广域网中采用的交换技术大多是__________。
CA.电路交换B.报文交换C.分组交换D.自定义交换2.下面关于网络信息安全的叙述中，正确的是__________。
CA.带有数字签名的信息是未泄密的B.防火墙可以防止外界接触到内部网络，从而保证内部网络的绝对安全C.数字加密的目的是使网络通信被窃听的情况下仍然保证数据的安全D.使用好的杀毒软件可以杀掉所有的病毒3.INTERNET中主机实现了TCP/IP所有的各层协议，而路由器一般只实现__________及其以下层协议的功能。
AA.网络互连层B.应用层C.传输层D.网络接口与硬件层4.Internet上有许多应用，其中特别适合用来进行文件操作（如复制、移动、更名、创建、删除等）的一种服务是__________。
D(B)A.EmailB.TelnetC.WWWD.FTP5.关于交换机和路由表的说法错误的是________。
CA.广域网中的交换机称为分组交换机或包交换机B.每个交换机有一张路由表C.路由表中的路由数据是固定不变的D.交换机的端口有的连接计算机，有的连接其它交换机6.利用Internet可实现许多应用服务，其中用来登录其它主机并直接操作使用该机资源的一种服务是________。
BA.EmailB.TelnetC.WWWD.FTP7.保证数据的完整性就是________。
BA.保证传送的数据信息不被第三方监视和窃取B.保证传送的数据信息不被篡改C.保证发送方的真实身份D.保证发送方不能抵赖曾经发送过某数据信息8.在计算机局域网中，以下资源中________不能被共享。
DA.处理器B.打印机C.硬盘D.键盘9.一个局域网通过一个路由器接入广域网，若局域网的网络号为202.29.151.0，那么路由器连接此局域网的端口的IP地址只可能为_________。
CA.202.29.1.1B.202.29.151.1C.202.29.151.0D.202.29.1.010.第五章由R、G、B三个位平面组成的彩色图像，若三个位平面中的像素位数分别为5,5,5，则最大颜色数目为________。
国际会计第四章练习
• 三、 True or False • 1. In high-inflation environment, countries use inflation-adjusted models to provide more decision-relevant information. (√ ) • 2. Many companies recognize internally generated brands as assets in Australia. (√ ) • 3. A weakness of the historical cost model is that it does not account for changes in the purchasing power of the currency that is used in the financial statements. (√ )
• 二、 Multiple Choice • 1. The reasons that recognized goodwill should be systematically amortized are • (AB ) • A. goodwill has a finite life and erodes over time. • B. the purchased goodwill is of necessity replaced by internally generated goodwill. • C. goodwill has an infinite life and even enhanced over time • D. systematically amortized is inherently arbitrary. • E. systematically amortized would result in a double hit against future earnings.
数据模型第一章到第四章部分习题答案
decision treeConclusion:Mary's optimal decision strategy is continue her outdoors show.decision tree (next page)Conclusion:Mary's optimal decision strategy in this case is continue her outdoors show.Exercise2.24Question （a）Let Z denote the annual return of investment E(Z)=0.5*E(X)+0.5*E(Y)=0.5*0.15+0.5*0.2=0.175∴SD(Z)=0.1253Conclusion :Expected return of investment is 0.175;the standard deviation of this return is 0.1253.Question （b）VAR(Z)=0.01615SD(Z)=0.12708VAR(Z)=0.01435SD(Z)=0.11979VAR(Z)=0.0148SD(Z)=0.12166VAR(Z)=0.01525SD(Z)=0.12349But expected return of investment is not change，is 0.175.∵VAR(Z)=0.5*0.5*VAR(X)+0.5*0.5*VAR(Y)+2*0.5*0.5*SD(X)*SD(Y)*CORR(X,Y)=0.25*0.025+0.25*0.036+0.5*0.05*0.06*0.3=0.0157if CORR(X,Y)=0.6if CORR(X,Y)=-0.6if CORR(X,Y)=-0.3if CORR(X,Y)=0.0Question （d）Exercise2.26Question （a）P=P(up)+P(down)=0.6*0.9+0.4*0.1=0.54+0.04=0.58Question （b）Question （c）∵P(Y=20)=20!/(0!*20!)P^20(1-P)^0=0.000019P(Y=19)=20!/(1!*19!)P^19(1-P)^1=0.000269P(Y=18)=20!/(2!*18!)P^18(1-P)^2=0.001849P(Y=17)=20!/(3!*17!)P^17(1-P)^3=0.008034P(Y=16)=20!/(4!*16!)P^16(1-P)^4=0.024725P(Y=15)=20!/(5!*15!)P^15(1-P)^5=0.057294∴0.0921896So the probability that the stock market movement in January will agree with the market movement for the entire year is 58%.So the probablility that the stock market will agree for all twenty years is 0.00186%.P(Y≥15)=P(Y=20)+ P(Y=19)+P(Y=18)+P(Y=17)+P(Y=16)+P(Y=15)=Question （d）Question （e）Exercise2.32Question （a）Must be satisfied these assumptions as follows:Question （b）∵x=0,1,…,6∴Question （c）We can find from the table of theprobility distribution of X,the probility that exactly three of the six customersQuestion （d）0.979796So the expected number of customers who will prefer thin crust pizza is 5;The satandard deciation of the number of customers who will prefer thin crust pizza is 0.979796.2 The probility of prefer thin is the same valup p for each and every one of the X prefers,and the probility of prefer thick then is aways 1-p for each and every one of the X prefers.SD（X）=sqrt(6*0.8*0.2)=E(X)=0.8*6=4.8≈5P(Y≥17)=P(Y=20)+ P(Y=19)+P(Y=18)+P(Y=17)=0.010170So the probility that the market movement in at least 15 to 20 years is 9.23896%.So the probility that the market movement in at least 17 to 20 years is 1.017%.1 Each prefer has exactly two possible outcomes:either the prefer is thin,or the prefer is thick.xx x x x X P --==620.080.0)!6)(!(!6)(。
计算机网络_第四章习题
计算机网络_第四章习题第四章1.在这个练习中，请使用本章中的一个公式，但在计算之前请先说明这个公式。
帧随机到达一个100 Mbps信道，并等待传输。
如果帧到达时信道正忙，那么它必须排队等待。
帧的长度呈指数分布，均值为10 000位/帧。
对于下列每一种帧到达率，试问平均一帧的延迟是多少(包括排队时间和传输时间)? (a) 90帧/秒。
(b) 900帧/秒。
(c) 9000帧/秒。
2. N个站共享一个56 kbps的纯ALOHA信道。
每个站平均每100秒输出一个1000位长的帧，即使前面的帧还没有被发送出去(比如，站可以将出境帧缓存起来)。
试问N的最大值是多少?3.考虑在低负载情况下纯ALOHA和分槽ALOHA的延迟。
试问哪个延迟更小?请说明你的答案。
4.一大群ALOHA用户每秒钟产生50个请求，包括原始的请求和重传的请求。
时间槽单位为40毫秒。
(a)试问:第一次发送成功的机会是多少? (b)试问:恰好k次冲突之后成功的概率是多少? (c)试问:所需传输次数的期望值是多少?5.在一个有无限用户的分槽ALOHA系统中，一个站在冲突之后到重传之间的平均等待时间槽数目为4。
请画出该系统的延迟与吞吐量之间的关系图。
6.试问在下列两种情况下CSMA/CD的竞争时间槽长度是多少?(a)一个2千米长的双导电缆(twin-lead cable )(信号的传播速度是信号在真空中传播速度的82%)? (b) 40千米长的多模光纤(信号的传播速度是信号在真空中传播速度的65% )?7.在一个使用基本位图协议的局域网中，最坏的情况下一个站(比如s)要等多久才可以传输它的帧? 8.在二进制倒计数协议中，试问为什么一个编号较低的站有可能得不到发送数据包的机会。
9.编号为1-16的16个站使用自适应树遍历协议来竞争一个共享信道。
如果所有站的地址预先设定，并且突然一次就绪，试问解决竞争需要多少个比特槽?10.考虑5个无线站:A, B, C, D和E。
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1 第四章 学前教育目标 一、填空 1.教育目标是一种给教育活动、教育过程设定的要在受教育者身上反应的 规格指标 ，它陈述的是要把受教育者培养成 什么样的人 。 2.广义的教教育目标的确定者可以是 家长 、教师，可以是某一个利益集团，也可以是整个社会。这种教育目标是具有 多样性 和 差异性 的。 3.是狭义的教育目标反映了一定社会对未来一代的 要求 、 期望 ，一般来说，它能较为科学地反映受教育者可能发生的变化，以及最终应该发生的变化。 4.学前教育目标的依据，首先是 儿童 ；了解儿童身心各方面的发展是确定教育目标必不可少的工作。其次是 社会 ；最后是 学科 ，对于学校教育来说， 学科 是很重要的目标生长点。但对学前教育来说，其重要性要低一些。 5.学前教育机构的学前教育目标，它严格按照国家的有关法律、法规制定和执行，具有明确地 计划性 和 目的性 。 6.学前教育目标是对培养幼儿 规格 的要求，也是对学前教育 最终结果 的反映和预期。 7.本世纪初，清朝政府颁布了我国历史上 第一个 学前教育法规——《奏定蒙养院章程》，这个《章程》提出了 3—7 岁幼儿保育教育的要旨，即保育、教育目标。 8.幼儿园教育的首要工作是确定 学前教育目标 。 9.布鲁姆教育目标的分类学中，提出了以 情感 、认知、动作技能三个领域的个体发展构架来确定相关的教育目标，其实质是教育目标“ 心理化 ”，以人的身心发展整体结构为出发点和归宿。 10.建国以来我国的三个学前教育目标从较多地强调 知识 教育发展到强调 能力 培养，从知识、能力并重发展到强调 个性 发展，强调 情感 发展。
二、名词解释 1.学前教育目标 2.幼儿园课程目标 3.幼儿园教育活动目标 4.幼儿园教育总体目标
三、问答 1.简述学前教育目标的意义 ①学前教育目标具有对幼儿教师思想和观念的规范作用 ②学前教育目标对教育过程的指导和控制作用 ③学前教育目标最本质的意义是对幼儿发展具有规范、评价（标准）作用
2.简述从学前教育目标的可操作性程度的学前教育目标层次 学前教育木匾的层次不同，其可操作性就有区别。越是具体的、下位的目标越具有可操作性。上位目标一定要分解为下位目标才能得以实施。 2
①是幼儿园教育总体目标。 ②是幼儿园课程目标 ③是幼儿园年龄阶段目标 ④是单元目标 ⑤是教育活动目标，也称教育行为目标
3.简述学前教育目标的结构 （一）学前教育目标的不同结构 ①从教育的基本内容的角度确定学前教育目标 即把学前教育的目标分为体育的目标、智育的目标、德育的目标和美育的目标。这四育的目标相互联系、有机结合，形成了学前教育目标的基本结构。 ②从学前教育目标的现实媒体——相关大的学科或领域表现教育目标 相关的领域表现的教育目标有健康领域的目标、自然领域的目标、社会领域的目标、艺术领域的目标、语言领域的目标等等。 ③从幼儿身心发展的角度确定学前教育目标 （二）布鲁姆的学前教育目标的分类 他再教育目标的分类学中，提出了以感情、认知、动作技能三个领域的个体发展构架来确定相关的教育目标，其实质是教育目标“心理化”，以人的身心发展整体结构为出发点和归宿。 分类如下： ①情感领域 ②认知领域 ③动作技能领域
4.简述1996年国家教委发布《幼儿园工作规程》中提出的学前教育目标的内涵。 5.简述建国以来，我国在三个不同的历史时期提出了三个学前教育目标的侧重点 建国以来我国的三个学前教育目标从较多地强调知识教育发展到强调能力培养，从知识、能力并重发展到强调个性发展，强调情感发展。
第五章 学前儿童体格、体能发展与教育 一、填空 1. 体格 、 体能 发展的状况和水平是衡量个体身体发展与健康水平的重要标志，也是影响个体心理发展的一个重要因素。 2.体格是指人体外表可观察或测量个体的 形态 、 结构 。包括人体生长发育的水平，身体的整体指数和比例（体型），以及身体的姿态等。 3
3.体格发展是指体格的生长发育；广义是指个体在其一生中身体的形态、结构和 生理机能 生长发育的变化过程，狭义是指身体发展的状况，如身高、体重、胸围、头围、脊柱弯曲的特征和限度、肩胛角的间距、足弓的测量指数、背力、左右手的握力、肺活量、心率指数、心搏量等发展、变化情况。 4.体能是指人体各器官、系统的技能在 体育活动 中表现出来的能力；体能发展指人体各器官系统技能能力的不断增强和提高，包括提高和发展 身体素质 、增强人体 基本活动能力 等。 5. 幼儿期 ，腿部生长加快，头部只占身体的六分之一左右，身体各部分比例逐渐接近成人。 6.学前儿童体格、体能发展教育的目标包括发展 身体的目标 、发展认知的目标、发展社会性和道德品质的目标、发展个性的目标。 7.身体练习是体格、体能发展教育最基本也是最重要的手段，活动内容主要包括基本动作、基本体操、排队和变换队形。 8.以游戏形式，有目的、有计划地开展多种多样的体育活动，积极发展幼儿的基本动作和身体素质 9.衡量体格发展的主要指标有： 体重比 、胸围比、坐高比和 柯普指数。 10.“三浴”即专门组织的空气浴、日光浴和水浴。 11.生活和活动环境要尽量做到“四化”，即净化、绿化、美化和儿童化。
二、名词解释 1.体格 2.体格的发展 3.体能 4.体能的发展 5.有氧耐力 6.平衡性能力 7.柔韧性能力 8.协调性能力 9.身体练习
三、问答 1.简述体格发展和体能发展的关系 体格发展与体能发展是相互联系、相互影响的。 ①强健的特哥是发展体能的物质基础。 ②身体素质的良好发展也影响着体格的发展。 ③人体基本活动能力的发展状况直接影响身体的生长发育和身体的体型及姿态。
2.简述学前儿童的体格发展的基本特征 ①体型特征：婴儿期的儿童，头大、躯干长、腿短，显得头重脚轻。幼儿期，腿部生长加快，头部只占身体的六分之一左右，身体各部分比例逐渐接近成人。 ②足弓特征：年龄较小的孩子，因皮下脂肪较多，故而脚掌心的内凹不明显，形成生理性平足。到3岁左右，因连接小骨的韧带和肌肉逐渐发达起来，脚掌心明显内凹。足弓的初步形成能避免因运动中振动而可能导致的对幼儿身体的损伤或其他潜在的不良影响， ③运动系统的特征：学前儿童运功系统的特点表明，科学地开展学前儿童的体格训练是什么必要的。 ④循环系统的特征：在幼儿期，该系统的机能已得到较大的发展和不断完善。 4
⑤呼吸系统的特征：幼儿期，幼儿呼吸系统的机能变化特征主要表现为没分钟呼吸频率由3岁时的约26次下降到4—7岁时的约22次，呼吸深度逐渐提高，肺换气量增加1—1.5倍，氧消耗量增加将近一倍。 ⑥神经系统的特征：幼儿期，儿童的神经细胞的数量和体积不断增多、增大，胸重量不断增加。
3.简述身体素质的发展特征 ①幼儿的力量素质较差 ②幼儿的耐力素质较差 ③幼儿的调整素质较差：调整素质是指力量和耐力素质以外的其他基本的身体素质的总称，主要包括平衡性、柔韧性、速度、灵敏性和协调性的能力
4.简述学前儿童体格、体能发展教育的目标 ①发展身体的目标 （1）促进幼儿身体正常发育和机能的协调发展 （2）培养身体的正确姿势 （3）发展幼儿的基本动作，使他们动作协调、姿势正确 （4）提高幼儿的身体素质 ②发展认知的目标 （1）帮助幼儿掌握身体活动的最基本知识和技能，发展有关概念，丰富他们的认知和经验 （2）提高幼儿智力活动的技能和品质，促进他们智力的发展 ③发展社会性和道德品质的目标 （1）发展幼儿团结友爱、相互合作、负责、服务、宽容、热爱集体等良好的社会情感和态度 （2）提高幼儿的社会交往能力 （3）培养幼儿文明礼貌、遵守纪律、爱护公物等良好的道德行为和习惯 （4）发展幼儿勇敢、坚强、不怕困难、刻苦耐劳、持之以恒等良好的意志品质 ④发展个性的目标 （1）培养幼儿积极参加体育活动的兴趣 （2）初步养成幼儿自觉和独立参与体育锻炼的习惯和能力 （3）培养幼儿活动开朗的性格
5.简述学前儿童体格、体能发展教育的内容 身体练习是体格、体能发展教育最基本也是最重要的手段 活动内容主要包括基本动作、基本体操、排队和变换队形
6.简述学前儿童体格、体能发展教育的原则 5
①身体全面发展原则 ②合理的运动负荷原则 ③从实际出发的原则 ④循序渐进的原则 ⑤多样化原则
7.简述学前儿童体格、体能发展教育的途径和方法 ①利用自然因素积极锻炼幼儿的身体 ②以游戏形式，有目的、有计划地开展多种多样的体育活动，积极发展幼儿的基本动作和身体素质 ③利用基本体操全面锻炼幼儿的是身体 ④建立良好的生活和活动环境 ⑤制定和执行合理的作息制度和严格的卫生保健制度 ⑥培养幼儿良好的生活卫生习惯 ⑦重视安全教育 ⑧重视幼儿的心理健康 ⑨重视合理的营养
第六章 学前儿童智能发展与教育 一、填空 1.智能也称智力或智慧，它是人们在获得知识和运用知识解决实际问题时所必须具备的心理条件或特征。 2.智能结构即智能是怎样组织和构成的。 3.J.P.吉尔福特的智力结构模型设想智能活动有三个维度：操作、内容及成果 4.R.卡特尔的智能结构理论认为智能包括两种一般因素：晶体智能和流体智能 5.皮亚杰认为智能是由运算结构决定的。 6.霍华德.加德纳认为人类发展基本的就是智能的发展，传统的智能测验并不能反映大多数人的智能水平，智能是由相对独立的功能性领域组成的并提出了八种不同的智能：言语智能、音乐智能、数理逻辑智能、空间智能、身体动作智能、人际关系智能、内省智能、博物智能。 7.儿童智能随着儿童年龄的增长，智能的稳定性逐渐也加强，智能核心随着儿童年龄的不同而产生变化，3岁前，主要是动作；4—5岁主要是图形知觉；而5—6岁，则主要是语言、数学。 8.男女幼儿在不同的智能因素的发展方面是不同的，或不平衡的，男性幼儿在数的推理与空间判断能力发表面有优势，而女性幼儿在言语流畅、机械记忆方面有优势。 9.遗传决定论认为智能发展主要受遗传因素的影响，高尔顿和高达德分别进行的名人研究和谱系研究是遗传决定论中两个较为典型的研究。 10.环境决定论是一种与遗传决定论相对立的学说，强调环境在智能发展中的决定作用。