彩色图像信号是由（）三种基色图像组成。
A.红
B.黄
C.绿
D.蓝
E.棕
参考答案：A, C, D
It was only after World War II had drawn to a close ______ in the United States.
A．did the baby boom begin
B．that the baby boom began
C．when the baby boom began
D．then the baby boom began
电阻点焊焊点分为（）
A、普通焊点
B、特殊焊点
C、一般焊点
D、关键焊点
