The driver was at______loss when________word came that he was forbidden to drive for speeding.[ ]

A. a; the  

B. /; /

C. the; the  

D. a; /

湿式减压蒸馏塔顶馏出物由（）组成。

A.减顶油、不凝气

B.减顶油和水蒸汽

C.减顶油、不凝气和水蒸汽

D.低分子烃和空气