问题
选择题
I____ asleep because it took me a long time to realize that the telephone was ringing.
A．could have fallen
B．should have fallen
C．must have fallen
D．mustn’t have fallen
答案
答案：C
考查虚拟语气。句意；我肯定是睡着了，因为用了很长时间我猜意识到电话铃一直在响。“must+have+done”表示对过去事情的肯定推测，译成“一定做过某事”。故选C。