— Why didn't you go to the cinema with us this afternoon? 

— I _____ at the station for my uncle from Beijing. [ ]

A. was waiting

B. have waited

C. am waiting

D. will wait

正常出流，圆柱形外管嘴的长度L与直径d之间，一般应该符合( )。

A．L=(2～5)d
B．L=(2～4)d
C．L=(3～4)d
D．L=(3～5)d