题目内容

硅烷或二氯硅烷与氨气反应,可以产生氮化硅。

A. 对
B. 错

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I was very disappointed not to be able to go to the jazz concert last Friday.The announcement in the paper said that you could buy1 at the theater box office in Richland Hills any day between 10:00 a.m.and 4:00 p.m..Since I work from 9 a.m.to 5:30 p.m.,the2time I could go to the theater was during my 45-minute lunch break.3,the theater is on the other side of the town,and the bus 4between my office and Richland Hills is not very good.5if you are lucky,you can make the round trip in 45 minutes.Last Monday I stood at the bus stop for fifteen minutes waiting for a bus.By the time I saw one come around the corner, there was not enough time6to make the trip so I gave7and went back to the office.The same thing happened on Tuesday,and8 on Wednesday.On Thursday,my9changed.I got on a bus right away and arrived at the theater10 exactly twenty minutes.When I got there,however,I found a long line of people at the box office.I heard one man say he had been waiting in line for11 an hour.12 I would not have enough time to wait in line,I13the next bus and headed back across the town.By Friday I realized my only 14was to make the trip by taxi.It was 15.But I felt it would be worth it to hear the concert.()1.A.food B.stamps C.tickets D.newspapers()2.A.early B.exact C.certain D.only()3.A.Surprisingly B.Luckily C.Unfortunately D.Surely()4.A.service B.driver C.seat D.stop()5.A.So B.Even C.As D.But()6.A.remained B.used C.left D.spent()7.A.away B.up C.in D.out()8.A.never B.again C.then D.more()9.A.time B.bus C.mind D.luck()10.A.in B.for C.at D.about()11.A.past B.over C.more D.beyond()12.A.RealizingB.Awaking C.Expecting D.Understanding()13.A.found B.waited C.caught D.missed()14.A.hope B.plan C.idea D.expression()15.A.cheap B.comfortable C.valuable D.expensive

虚约束没有独立约束作用,在实际机器可有可无。

一个作平面运动的构件有2个独立运动的自由度。

平面低副机构中,每个转动副和移动副所引入的约束条件是相同的。