Man: I'm still waiting for my sister to come back and type the application letter for me.Woman: Why bother her I'll show you how to use the computer. It's quite easy.Question: What does the woman mean

A．She'll type the letter for the man.

B．She'll teach the man to operate the computer.

C．She doesn't think his sister is a good typist.

D．She thinks the man should buy a computer.

目前施工常用的混凝土输送管多为壁厚为（）mm的电焊钢管。

A、5

B、4

C、3

D、2