Question

He ________ without saying good — bye tothem, for he always has good manners.

1. A.
   mustn’t have left
2. B.
   may not have left
3. C.
   shouldn’t have left
4. D.
   can’t have left

Answer 1

D
can’t表示可能性最小，最不可能，因为后面说他总是很有礼貌。