—We can use QQ to talk with each other on the Internet.

—Really? But can you tell me _______it.

A．how I can use

B．how can I use

C．why can I use

D．when I can use

太阴病误下所致"胸下结硬"，其病机是（）

A.脾阳愈虚，寒湿凝滞，气机不通

B.脾阳愈虚，表邪乘虚内陷，气机不通

C.寒邪结于胸膈，气机不通

D.水饮结于胸膈，气机不通

E.以上都不是