English is a language that many people around the world _______ not speak perfectly but at least _______ understand.

A．might；could

B．will；must　

C．would；might

D．can；may

闪蒸循环泵的作用是闪蒸酸浴进行（）的动力。

A、循环

B、过滤

C、加热

D、蒸发