12.Some metals are better conductors of electricity than oth

12.Some metals are better conductors of electricity than others,______ means that the former have atoms containing more free electrons than latter.
A.that B.this C.which D.it
13.If the earth suddenly ______ spinning,we would all fly off it.
A.had stopped B.stopped
C.has stopped D.would stop
14.They hurried there only to find the meeting canceled.In fact,they ______ at all.
A.might not have gone B.needn't have gone
C.mustn't have gone D.wouldn't have gone
15.The time has come ______ we make extensive use of nuclear energy.
A.when B.while C.as D.since
16.You and I could hardly understand each other,_________?
A.could I B.couldn’t you
C.could we D.couldn’t we
17.You ______ a new bicycle,since the one you lost the other day has already been found.
A.should not buy B.need not buy
C.need not have bought D.should not have bought
18.They _______ in spite of the extremely difficult conditions.
A.carried out B.carried on C.carried off D.carried forward
19.Children who are over-protected by their parents may become _______.
A.hurt B.damaged C.spoiled D.harmed
20.When Mr.Jones gets old,he will _______ over his business to his son.
A.take B.hand C.think D.get
21.His understanding made a deep impression _______ the young girl.
A.in B.on C.for D.to
22.They have been trying to arrive at a practical solution _______ the problem.
A.in B.to C.on D.with
23.In many American families,parents feel that children should make important
decisions _______.
A.to themselves B.on themselves C.of themselves D.by themselves
24.I find this treatment very _______ to my health.
A.advisable B.invaluable C.beneficial D.worthy
25.As a _______ president,his views are treated with respect when he is interviewed.
A.prior B.previous C.late D.former
26.It is not difficult to _______ the idea that machines can communicate information to us.
A.admit B.receive C.accept D.convince