北交20春《大学英语1》在线作业二_822答案

(单选题)1: 当输入信号的复频率等于系统函数的零点时，系统的强迫响应分量为（）。

A: 无穷大
B: 不为零的常数
C: 0
D: 随输入信号而定
正确答案: C
(单选题)2: 满足傅氏级数收敛条件时，周期信号f(t)的平均功率（）。

A: 大于各谐波分量平均功率之和
B: 不等于各谐波分量平均功率之和
C: 小于各谐波分量平均功率之和
D: 等于各谐波分量平均功率之和
正确答案: D
(单选题)3: 卷积δ(t)*f(t)*δ(t)的结果为（）。

A: δ(t)
B: δ(2t)
C: f(t)
D: f(2t)
正确答案: C
(单选题)4: 信号的时宽与信号的频宽之间呈（）。

A: 正比关系
B: 反比关系
C: 平方关系
D: 没有关系
正确答案: B
(单选题)5: 设一个矩形脉冲的面积为S，则矩形脉冲的傅氏变换在原点处的函数值等于（）。

A: S/2
B: S/3
C: S/4
D: S
正确答案: D
(单选题)6: 线性系统具有（）。

A: 分解特性
B: 零状态线性
C: 零输入线性
D: 以上全对
正确答案: D
(单选题)7: 如果一连续时间二阶系统的系统函数H(s)的共轭极点在虚轴上，则它的h(t)应是（）。

20春《大学英语（三）》作业4试卷总分:100 得分:100一、单选题(共25 道试题,共100 分)1.Energy is ____makes thing work..A.whatB.somethingC.anythingD.that答案:A2.Tests help you make your new knowledge_____.A.easyB.difficultC.oldD.permanent答案:D3.The nurse took a(n)___ of my blood for tests.A.sortB.typeC.exampleD.sample答案:D4.After resting for a few weeks,John set_____once more.A.aboutB.offC.onD.up答案:B5.We all elected Lin Hui ____ monitor of our class.A.theB.aC./D.as答案:C6.He flew from Europe to Tokyo by the_____across the Pole.A.courseB.routeC.mayD.routine答案:B7.Call me when you are ___ leisure.A.onB.inC.atD.of答案:C8.The idea _____ to him in his dream and he decided to carry it out.A.happenedB.struckC.appearedD.occurred答案:D9.How many more exercise-books do you have ___?A.to correctB.to be correctedC.for correctingD.corrected答案:A10.If you smoke in a non-smoking section people _____.A.have objectedB.objectedC.must objectD.will object答案:D11.The thief _____ in from the kitchen window as all the other windows and doors were closed.A.may climbB.must have climbedC.could climbD.should have climbed答案:B12.Doing all the housework ___ my mother at least three hours a day.A.spendsB.affordsC.occupiesD.spares答案:C13.He has lived here for years,_________ nobody knows what he is.B.thoughC.and yetD.for all that答案:C14.The manager assured the customer that his complaint would be soon seen _____ .A.atB.toC.onD.by答案:B15.Only guests of the hotel enjoy the _____ of using the private beach.A.possibilityB.privilegeC.favorD.advantage答案:B16.Everybody _____ but me has gone to the party.A.allB.elseC.othersD.together答案:B17.This watch is not worthy ________ the gold belt.A.inB.atC.ofD.with答案:C18.How close parents are to their children can produce some strong influence _____ their children.A.inB.atC.onD.for答案:C19.The children_____(e)d with fear when they saw the policeman.A.quiverC.trembleD.shiver答案:C20.Each of you ______ responsible for the accident.A.amB.beC.isD.are答案:C21.An expert is_____who has special knowledge, skill or training.A.thatB.oneC.whichD.such答案:B22.Myra was busy, because her husband had been made _____.A.a MayorB.the MayorC.MayorD.of Mayor答案:C23.The school bus was ___ by a thick fog.A.held upB.broken offC.kept upD.put off答案:A24.He is worried a lot now, for he has lost a _____of keys today.A.massB.pileC.pieceD.bunch答案:D25.When he learned he had passed the exam, Tom _____ song.A.broke outB.broke inC.broke intoD.broke through 答案:C。

福师20春《大学英语（1）》在线作业一试卷总分:100 得分:100一、单选题(共50 道试题,共100 分)1.—Hurry up please, or I'll be late. —_______A.Sorry sir, but the traffic is thick now.B.Well, it's alright, sir.C.How can you say that, sir?D.Oh, we are going the right way.答案:A2.The Red Army seized the land and _____ it to the poor peasants.A.attributedB.distributedC.contributedD.assigned答案:B3.If you refuse to go to the party,____________.A.so would sheB.so does sheC.so will sheD.neither will she答案:C4.The complicated problem can be solved by the computer within ____________ a few seconds.A.evenB.justC.exactD.very答案:B5.Jack____________ in the street when I____________on him.A.walked... calledB.was walking ... was callingC.walked ... was callingD.was walking...called答案:D6.She's the only child in her family, but they didn't really _______ her.A.hurtB.damageC.spoilD.harm答案:C7.I'd rather have a room of my own, however small it is, than____________a room with someone else.A.to shareB.to have sharedC.shareD.sharing答案:C8.Without the _______ of TV, children might spend more time reading and writing.A.watchingB.concentrationC.showD.distraction答案:D9.I went to the post office，only_____ it was closed．A.findingB.to findC.to be findingD.found答案:B10.This TV program is very good.Everybody in my family ____it.A.to watchB.watchesC.watchsD.watched答案:B11.In such dry weather, the flowers will have to be watered if they____________.A.have survivedB.are to surviveC.would survivedD.will survive答案:B12.John does a lot of housework every evening, but now he ____________his schoolmates with their lessons.A.helpB.is helpingC.helpsD.has helped答案:B13.The red rose is her __________.A.favorB.favoriteC.likeD.best答案:B14.If you have made a decision, please stick _______ what you want.A.toB.upC.ofD.for答案:A15.The bank is reported in the local newspaper____________ in broad daylight yesterday.A.robbedB.to have been robbedC.being robbedD.having been robbed答案:B16.— Would you like to have dinner with us this evening? — ________.A.OK, but I have to go to a meeting nowB.No, I can'tC.Sorry, but this evening I have to go to the airport to meet my parentsD.I don't know答案:C17.I found ___ to answer all the questions within the time given.A.no possibilityB.there was impossibilityC.impossibleD.it impossible答案:D18.The _____ of yourself that you see in the mirror is produced by the reflection of light.A.lookB.figureC.imageD.appearance答案:C19.—Hi, is Mary there, please? —______A.Hold on. I'll get her.B.No, she isn't here.C.Yes, she lives here.D.Yes, what do you want.答案:A20.We can't ___ one to change the habits of a lifetime in a short time.A.hopeB.waitC.expectD.imagine答案:C21.Seeing the police coming, away____________ .A.the thieves ranB.had the thieves runC.ran the thievesD.did the thieves run答案:C22.It was ______fun to play on the beach that it attracted countless children.A.such greatB.so greatC.such a greatD.so great a答案:A23.He ____________ not to leave waste paper in public places any more.A.warnsB.warnedC.is warnedD.was warned答案:D24.He ____________the Communist Party____________2002.A.has joined, inB.has joined, sinceC.joined, onD.joined, in答案:D25.After her husband died, she ___ another man in 1964.A.marriedB.married withC.married toD.was married to答案:A26.The storm prevented Betty and Mary ___ yesterday.A.leaveB.to leaveC.from leavingD.of leaving答案:C27.He and his family had to ______ on 50$ a week.A.payB.spendC.liveD.exist答案:B28.Either Mr. Lee or the students______ to clean the blackboard.A.hadB.hasC.haveD.having答案:C29.If you study hard, you____________the examination.A.has passedB.are passingC.have passedD.will pass答案:D30.Everything seems all right, ____________ ?A.doesn't itB.won't itC.hasn't itD.don't they答案:A31.We can go when the ground____________.A.is dryingB.has driedC.driedD.dry答案:B32.—Could you be so kind as to turn down that rock “n” roll? I am pre paring for tomorrow's exam. —________A.It's none of your business.B.What are you doing?C.Sure. Sorry to disturb you.D.No, I don't think so.答案:C33.There____________more than 300,000 kinds of plants on the earth.A.isB.are existingC.existsD.exist答案:D34.He could do nothing but____________for the bus____________.A.wait ... to comeB.wait ... comeC.waiting ... comingD.waited ... came答案:A35.If you____________quiet, I'll tell you what happened.A.beB.are to beC.areD.will be答案:C36.He used to have a _____________ of stampcollecting but he has given it up.A.habitB.hobbyC.customD.like答案:B37.One____________if one breaks the law.A.will be punishedB.will punishC.is being punishedD.has been punished答案:A38.We have come to a critical moment. You must take immediate ___.A.actB.actionC.activityD.doings答案:B39.—Are you getting a new flat this year? —____ I can't afford to pay my bills, let alone buy a new flat.A.Without question.B.You must be joking.C.Good idea!D.Are you sure?答案:B40.— You should have thanked her before you left.— I meant____________, but when I was leaving I couldn't find her anywhere.A.to doB.toC.doingD.doing so答案:B41.The purpose of new technology is to make life easier,____________it more difficult.A.not makingB.not makeC.not to makeD.nor to make答案:C42.There are many sheep____their farm.A.atB.inC.onD.within答案:C43.I suppose you're not serious, ____________ ?A.don't IB.do IC.aren't youD.are you答案:D44.He was ________ the Nobel prize for his new discovery.A.offeredrmedC.rewardedD.awarded答案:D45.Robert is said ____________abroad, but I don't know what country he studied in.A.to have studiedB.to studyC.to be studyingD.to have been studying答案:A46.The President____________ went to see the flood-stricken areas.A.himselfB.didC.is saidD.has答案:A47.—You have lovely children. —_______________.A.No, no, no. They are notB.Oh, no, noC.You're talking too muchD.Thanks答案:D48.The event ____________ at the time last year.A.happensB.happenedC.is happenedD.was happened答案:B49.I have no doubt ____ he will overcome all his difficulties．A.whichB.whatC.thatD.if答案:C50.The problem of housing____________ lead to the problem of social instability.A.itselfB.mustC.didD.never 答案:C。

D:I’d come to help
答案：B
— Could you give me a helping hand?
—____________________
—I want to clean my room.
A:How is that?
B:Sure, what can I do for you?
C:Not at all.
20春《大学英语1(本科)》在线作业3
I was giving a talk to a large group of people, the same talk I ______ to half a dozen other groups before.
A:was giving
B:am giving
C:had given
What are you going to do?
A:I'm planning to go to the cinema with my friend.
B:No, I'm not going to do it.
C:Thank you for asking me about it.
D:Yes, I'll go.
D:Which one?
答案：A
_______ tomorrow’s lessons, Frank has no time to go out with his friends.
A:Not preparing
B:Not having prepared
C:Not to prepare
D:Being not prepared
A:which
B:then
C:when
D:that