The man in blue must be your brother, _____?
A.mustn’t he
B.needn’t he
C.isn’t he
D.is he
答案:C
What's ___________ breakfast?[ ]
A. for
B. of
C. to
往复泵、回转泵属于()。
A.动力式泵
B.容积式泵
C.直联式泵
D.水环式泵