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.

我顶richardtung

是不是新概念的啊、、、
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是某国人。
4，had to 前面说出了原因，后面就“不得不”这样做了。“他把方案忘在家了，所以他不得不回云取。”这里也没必要推测，因为“他”不得不这样做。
5，must have been这是对为什么没听见电话的一种推测，她不可能“不得不”在睡觉。
总之：虚拟语气表示推测，而且很强烈，而had to表示非此不可，不必推测。

must have been
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我只是凭感觉做的，错了不好意思哈．

must have been
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看后面是动词就用had to
是名词就用must have been

1.must have been
2.must have been
3.must have been
4.had to
5.had to
6.must have been
must have been 是表示根据现在的实际情况而进行的主观的一种推测！
had to 是表示对于现实的一种无奈的接受！有点不乐意，又没有办法的含义！

must have been
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must have been
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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...

1 must have been
2 nust have been
3 must have been
4 had to
5 had to
6 must have been
must have been 表主观猜测
had to 表被动接受