问题 单项选择题

某单位利用业余时间组织了3次义务劳动,总计有112人次参加。在参加义务劳动的人中,只参加1次、参加2次和3次全部参加的人数之比为5:4:1。问该单位共有多少人参加了义务劳动?

A.70 

B.80 

C.85 

D.102

答案

参考答案:A

解析:解析 3次义务劳动共计112人次参加,其中只参加1次,参加2次和3次全部参加的人数之比为5∶4∶1。设设只参加一次的人数为5x人,则参加2次的为4x人,参加3次的为x人。根据三集合容斥原理公式可列式为:112=5x+4x×2+x×3,解得x=7,则参加了一次的人数为35人,参加2次的人数为28人,参加3次的为7人,参加总人数共计35+28+7=70人,故正确答案为A。 考点:容斥原理问题

完形填空
At the beginning of my 8:00 a.m.class one Monday at University of Nevada,Las Vegas(UNLV),I cheerfully asked my students    their weekend had been.“Not been very good”,one young man said.He'd had his wisdom teeth      .The young man then went on to ask me why I   seemed to be so cheerful.His question reminded me of    I′d read somewhere before:”Every morning when you get up,you have a     about how you want to approach life that day”,I said.“I choose to be cheerful”.
“Let me give you an    ”,I continued.The other 60 students in the class     their chatter and began to listen.one day,my car died on the way.I called AAA and asked them to send a     .The secretary in the Provost’S office asked me what had happened.”This is my      day”, I replied,smiling.”Your Car      and today is your lucky day?”She Was      .”What do you mean?”“I live 17 miles from here”,I replied.”My car    have gone wrong anywhere along the freeway.It didn’t.Instead,it went wrong in the      place:off the freeway,within walking distance of here.I’m     able to teach my class,and I’ve been able to arrange for the tow truck to    me after class.”The secretary’s eyes opened wide,and then she smiled.
I scanned the 60 faces in the lecture hall.    the early hour,no one seemed to be asleep.Somehow,my story had    them.Or maybe it Wasn’t the story    .It had all started with a student's      that I Was cheerful.A wise mail once said:”Who you are     louder to me than anything you can say”.I suppose it must  be so.
小题1:
A.howB.whatC.whetherD.where
小题2:
A.pulledB.broughtC.takenD.removed
小题3:
A.seldomB.alwaysC.occasionallyD.ever
小题4:
A.somethingB.nothingC.anythingD.everything
小题5:
A.decisionB.chanceC.choiceD.destination
小题6:
A.excuseB.explanationC.instruction  D.example
小题7:
A.stoppedB.interruptedC.disturbed  D.prevented
小题8:
A.truckB.tractorC.secretary  D.policeman
小题9:
A.strangeB.terribleC.lucky  D.pleasant
小题10:
A.cuts upB.breaks upC.breaks downD.tears down
小题11:
A.cheerfulB.doubtfulC.puzzled  D.worried
小题12:
A.couldB.mustC.should  D.would
小题13:
A.wrongB.properC.perfect  D.smooth
小题14:
A.thus  B.stillC.hardly  D.even
小题15:
A.pick  B.sendC.meet  D.visit
小题16:
A.DespiteB.AlthoughC.Since  D.Though
小题17:
A.taughtB.touchedC.educated D.excited
小题18:
A.after all B.in allC.above all D.at all
小题19:
A.motivationB.inspirationC.observation D.appreciation
小题20:
A.says B.speaksC.talks D.tells
选择题