There is no light in the room.They asleep.A. should have gone toB. must beC. could goD. mi

问题补充：

There is no light in the room.They asleep.

A. should have gone to

B. must be

C. could go

D. might be going

答案：

A. should have gone to

(答案→)B. must be

C. could go

D. might be going

解析：must表示推测，意思是“一定，必定”。