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形式上否定主句的谓语，实际上是否定从句的谓语

当动词think, believe, suppose, imagine, expect, feel的主语是第一人称、谓语动词为没有任何副词修饰的一般现在时，它们的否定式实际上是对宾语从句的否定。表示说话者提出一种委婉的看法或主张。如：

I think that he will help us. —I don't think that he will help us. 我认为它不会帮助我们。

I believe that he is right. —I don't believe that he is right. 我认为他不对。

I suppose that he likes it. —I don't suppose that he likes it. 我想他不喜欢它。

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for, during, through

(A) for后接“一段时间”，表示某事持续多久，多与完成时连用。如：

She has been ill for several days. 她已经病了几天了。

(B) during表示“在……期间”。如：

I went to France for two weeks during the summer. 夏天我去了法国两个星期。

(C) through表示“一直……，自始至终”。如：

They worked hard through the winter. 整个冬天他们都在努力工作。

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