胸部高电压摄影，滤线栅的栅比不应小于（）
A.8：1
B.10：1
C.12：1
D.16：1
E.18：1
参考答案：C
There was a girl _____ on the playground. [ ]
A. play
B. to play
C. played
D. playing
You as well ________ right.
A．I are
B．I am
C．as I am
D．as I are
