Question

完成以下句子，用had to或must have been填空。

Example：
He is very tired because he had to get up early this morning.
He didn't get up early this morning. He must have been tired.
1 He didn't come to work yesterday. He ______ ill.
2 He didn't come to the office this morning. He ______ stay at home.3 I don't think she was Austrian. She ______German.
4 I lost my pen so I ______ buy a new one.
5 He forgot his case so he ______ return home.
6 She didn't hear the phone. She ______ sleeping.

绝对采纳～～

Answer 1

我不知道“must have to”你是怎么想出来的，或者在哪里出现，如果有出处，请指教；如果是你自己想出来的，请解释下理由。
我的理解：must have to根本就不可能存在，要亮伏判表示主观就用must，要表示客观就用have to， 如果想表达主观和客观上都必须，那就用should或者其他词。所以对于第一题并不是because的原因.
题外话，第一句的逻辑不恰当，直白点，什么狗屁题目，要考查have to和must的知识点就换个题目敬改，he is tired now because he got up early this morning.他现在很累是因为他今天早起。不需要强调主观或者客观，had to 多此一举。
must和have to的区别可参考：http://zhidao.baidu.com/question/38217240.html
第二题，must have been doing sth. 不是stay，而是staying。
must be和 must have to的区别请参考http://zhidao.baidu.com/question/126309754.html
综上厅则所述，基础知识没有掌握。

Answer 2

Example：
He is very tired because he had to get up early this morning.
He didn't get up early this morning. He must have been tired.
1 He didn't come to work yesterday. He【must have been】 ill.
2 He didn't come to the office this morning. He【had to】stay at home.
3 I don't think she was Austrian. She 【must have been】German.
4 I lost my pen so I 【had to】 buy a new one.
5 He forgot his case so he 【神液茄had to】 return home.
6 She didn't hear the phone. She 【埋喊must have been】游察sleeping.

追问

为什么这么填？？

追答

1. had to  “不得不”，后接动词原形

2. must have been "肯定..." 表示一种肯定的推测，后接v-ing，名词或者形容词均可！

通过词义和后接词两种方法都可判定。

Answer 3

1，must hve been
2. had to ?
3, must have been
4, had to
5, had to
6, must have been

追问

为什么这么填？？

追答

你可以看一个句子是否已经有动词
如果没有，大部分填must have been
如果有，就一定填had to，因为一个句子不能有2个动词！