答案：where→that/which或去掉where

　　2. This is the watch for which Tom is looking.

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　　解析：英语中，有些短语动词，介词或副词不可与动词相分离。又如：look after run into等。

　　答案：把for放在looking之后

　　3. The person to who you spoke is a student of Grade Two.

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　　解析：尽管在口语中who whom都能作宾语，但在介词后只能用whom。

　　答案：who→whom

　　4. The house in that we live is very small.

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　　答案：that→which

　　5. The sun gives off light and warmth that makes it possible for plants to grow.

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　　解析：that不可以引导非限制性定语从句。

　　答案：that→which

　　6. I've read all the books which I borrowed from the library.

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　　解析：当先行词被all every no some any little等修饰时，常用that引导定语从句。

　　答案：which→that或去掉which

　　7. This is the best film which I have ever seen.

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解析：当先行词被序数词、形容词的最高级或the only the very等所修饰时，常用that引导定语从句。