There ia no light in the room. They ___ asleep.

A．should have gone to

B．must be

C．could go

D．might be going

拖带中应防止的横拖现象是指：（）

A.拖轮横拖大船舶首，船尾或船中

B.拖缆方向垂直于拖轮首尾面

C.拖轮与大船首尾面平行，拖缆与两船首尾面垂直

D.拖缆张力和拖轮拖力的合力方向与拖轮首尾面垂直