用had to 或 must have been填空.

题目

用had to 或 must have been填空.
He didn't come to work yesterday.He ____ill.
He didn't come to the office this morning.He ______stay at home.
I don't think she was Austrian.She _____German.
I lost my pen so I _____buy a new one.
He forgot his case so he _______ return home.
She didn't hear the phone.She _____sleeping.
请说说他们有什么区别.

答案

1,must have been 虚拟语气,表推测,意思是一定2,had to 因为没有推测的意味,表是原因,意思是不得不3,must have been 可以翻译过来试试就知道了.因为不可能有“不得不是某国人”这样的句子的.所以只能是推测某人可能...