根据下面提供的对话情景，从下列7个选项中选择正确答案，使对话连贯、完整。其中有两项是多余的。

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．