Question

Look! Tom is too sleepy to work．He _______ up watching TV．

1. A.
   mustn’t have stayed
2. B.
   shouldn’t have stayed
3. C.
   mustn’t stay
4. D.
   ought not to say．

Answer 1

B

从上句Look! Tom is too sleepy to work．说明他本不该熬夜看电视，而实际上是熬夜导致太困了。shouldn’t have done是“本不该做…而实际上却做了”。