问题补充:
Mary my letter; otherwise she would have replied before now.
A. has received
B. ought to have received
C. couldn’t have received
D. shouldn’t have received
答案:
A. has received
B. ought to have received
(答案→)C. couldn’t have received
D. shouldn’t have received
解析:考查情态动词用法。关键后半句:要不然,她之前就会给我回信。根据这里的would have replied可知是对过去情况的虚拟,那么前一句也应该是对过去情况的推测。结合句意可知C正确。句意:玛丽不可能收到我的信得。要不然之前就会给我回信的。