根据对话内容，在方框中选择正确的答案补全对话。

A: Hello! May I speak to Mr Smith?

B: I'm sorry.1.I think he'll be back in an hour.2.

A: That's very kind of you. I'd like him to come to my birthday party.     3  

B: OK.4! I'll go and got a pen and a piece of paper. OK.5.

A: 5697846．My name is Liu Wei.

B: All right.6.

焊接接头构造形式中的盖板接头、套管接头、塞焊接头，其实质上应属于变形的( )。

A．对接接头

B．搭接接头

C．角接接头

D．端接接头