－Why didn’t you go to the cinema with us this afternoon, Jim?

－Because I ______ at the station for my uncle from Beijing at that time.

A．was waiting

B．have waited

C．am waiting

D．will wait

自动曝光探测器应安装在

A．控制台内
B．X线管窗口处
C．胶片暗盒下面
D．肢体和滤线栅之间
E．滤线栅和暗盒之间