Question

（2007天津寶坻一模模擬）I didn't hear the bell ring; I ________ asleep.

1. A.
   must be
2. B.
   must have been
3. C.
   should be
4. D.
   should have been

Answer 1

B
句意：我那時沒有聽到鈴響，一定是睡著了。根據(jù)前面didn't hear...的提示，可知本題是對過去狀態(tài)的推測，故排除A、C兩項；表肯定推測B符合題意，而D表示本應該做而實際沒有做的概念。