– Mother’s Day is coming. I’ve no idea______________for my mother.

--Hmm, maybe you can do the housework.

A．what I should buy

B．how should I do

C．what I should do

D．where should I go

叶片式流体机械的反作用度，则说明该机器的转轮叶片是（）叶片。

A.反击式；

B.冲击式；

C.后弯式。