The telephone rang but I didn’t hear it. I asleep.A. must beB. ought to have beenC. shoul

问题补充：

The telephone rang but I didn’t hear it. I asleep.

A. must be

B. ought to have been

C. should be

D. must have been

答案：

A. must be

B. ought to have been

C. should be

(答案→)D. must have been

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