电视机等家用电器的开启、关闭及频道转换，可以通过遥控器实现，遥控电视机的光是[ ]

A．红光

B．红外线

C．紫光

D．紫外线

补全对话。

A: Today we are going to talk about a great invention. It looks like a human being.   1    

B: It's a robot.    2    

A: Of course not. The first robot was invented in 1921.

B:    3    

A: Sure. They can take the place of humans to do some boring work. They can also do a lot of dangerous

work instead of humans.

B:    4    

A: No. Robots can do a lot of work instead of people in many ways, but people wouldn't be replaced by

robots.    5    

B: We get it.

A. Is that clear?

B. Can it do some washing?

C. Why do you think it is useful?

D. It appeared several centuries ago, didn't it?

E. Will robots be the same as people?

F. What is it?

G. Could you please tell me more about robots?