___ impressed me most about the woman was that she looked after the old man for twenty years without any complaint.

A．That

B．Which

C．What

D．As

轴流压缩机利用叶片和气体的相互作用，提高气体的压力和动能，并利用相继的通流元件使气流减速，将（）转变为压力的提高。

A.势能

B.动能

C.静压能

D.惯性力