Question

The teacher said to the students,“You ________ your homework yesterday but none of you did so.”

1. A.
   should finish
2. B.
   must finish
3. C.
   ought to do
4. D.
   should have done

Answer 1

D
should have done表示“本该做而没有做的事情”，而shouldn't have done表示“本来不该做而做了的事情。”