1 . 普鲁士国王威廉一世决不可能想到他送给俄罗斯人民的厚礼会有这样一段令人惊讶的历史。
Frederick William I, the King of Prussia, ________ never ________ ________ that his greatest gift to the Russian people would have such an amazing history.

2 . ----- Mary looks very upset. She _______ failed to pass the exam.
----- I guess so. It's very difficult after all.

A．must have

B．could have

C．should have

D．might have