A.they operate between 150 and 450 rpm
B.they are connected to the propeller by gearing
C.their smaller size and weight
D.they can be connected directly to the propeller without gearing
[试题]4.Why is the conquest of space more than a great a[A]Becauseitisfullofchallengesforhumanbeings.[B]Becauseitmaybenecessaryforhumanbeingstosurvive.[C]Becauseitisthegreatestadventureinhumanhistory.[D]Becauseitismoreexcitingthananyotheradventures.
[单选题]Why didn't Peter take more money from the bank?A.He was afraid that be would be caught on the spot.B.The maximum sum allowed was $5,000.C.He was limited by time and the size of his pockets.D.Large bills were not within his reach.
[单选题]( )More and more waste has __________ a lot of space.We should do something to reduce it.A.taken placeB.taken awayC.taken upD.taken off
[单选题]More and more young people are trying to do something _____ the old.A. served B. to serve C. serve D. serves
[单选题]More and more persons who use the Intemet had created a (74) or web based diary.(74)A. blogB.DBMSC.profileD., photo-set
[单选题]More and more high——rise buildings have been built in big cities space.A.in search ofB.in place ofC.for lack ofD.for fear of
[单选题]Why have some people begun to place less emphasis on work and more on non-w
[单选题]A.In China,more and more middle school students are getting shorter sleeping time than be-fore. Most students sleep less than nine hours every night,because they have much homework to do. Some homework is given by their teachers,and some by their par
[单选题]A.ccording to the author, the reason why we go wrong about our friends is that ______.A.)we fall to listen carefully when they talkB.)people tend to be annoyed when we cheek what they sayC.) people usually state one thing hut means anotherD.)we tend
[单选题]A.ccording to the author, the reason why parental divorce has greater effect on boys than on girls is that_____.[A] all cultures encourage male aggression and noncompliance[B] boys are always involved in their parents’ fights[C] males are usually vie