直流电机电刷的极性由线圈内的()方向来确定。

题型:填空题

问题:

直流电机电刷的极性由线圈内的()方向来确定。

考点:电力机车电工考试高级机车电工高级机车电工题库
题型:填空题

阅读下面短文,用所给动词的适当形式填空,使短文完整、通顺。每空不限一词。

Rose is one of the funniest girls in her class. She looks like a boy, and she is good at performing. So she 小题1:_________(choose) to play Harry Potter by her classmates last week. She said happily, “I’m sure that I am able to do the job well because I小题2:_____(see) the movie many times already.”

Dick, one of Rose’s best classmates, is also an actor in the play. He 小题3:_________(like) to perform the play with Rose. He said, “We are confident that we 小题4:________(do) well in our school art festival next week.”

Mrs. Smith, their teacher, pays much attention to their play. She often encourages them. Yesterday afternoon when she小题5:_________(watch) their performance, she took photos of them.

题型:填空题

下列命题中,a、b、c表示不同的直线,α,β表示不同的平面,其真命题有(  )

①若a⊥b,b⊥α,则aα

②若a⊥α,b⊥α,则ab

③a是α的斜线,b是a在α上的射影,c⊂α,a⊥c,则b⊥c

④若a⊂α,b⊂α,c⊥a,c⊥b,则c⊥α

A.1个

B.2个

C.3个

D.4个

题型:填空题

下列各组物质之间属于同系物的是______,属于同分异构体的是______.

A.CH3CH3与CH4

B.C3H8与CH3CH2CH3

C.CH2=CHCH3与CH2=CH-CH=CH2

D.CH2=CH-CH=CH2与CH3CH2C≡CH

E.乙烷与2-甲基丁烷.

题型:填空题

All the survivors of the flight disaster are out of danger and being well ____to in the hospital.

A attended   B  referred    C  brought    D  pointed

题型:填空题

不论是服务器、工作站,还是各种网络设备的选择,首先应考虑其运行的( ),这是系统正常运行的基础。

A.适用性

B.可靠性

C.时效性

D.准确性

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