变为否定句时，some要变成any,and也要变成or。如果是做肯定句变否定句的题目时，some一定要变成any。如：I bought some apples.变：I didnt buy any apples.变疑问句时，some要变成any，但是and不能改成or。

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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。