—Tomas Edison always ________ too late, because he thought sleeping at night is to waste time.

—Oh. He was really a strange man.[ ]

A. put up            

B. stayed up

C. woke up            

D. got up

交流换向器电动机因有滑坏及换向器故外加电压不能过高，容量（）。

A、可以做得很大

B、不会很大

C、3KW以下

D、800瓦以下