Mr. White _____ at 8:30 for the meeting, but he didn't' show up. [ ]

A. should have arrived

B. should arrive

C. should have had arrived

D. should be arriving

在开车过程中，蒸汽再沸器在投用时，引物料的速度（）比较好。

A.越快越好

B.先快后慢

C.越慢越好

D.先慢后快