请找出下列各句中的错误并加以改正。
1. This is the factory where we visited last week.
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2. This is the watch for which Tom is looking.
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3. The person to who you spoke is a student of Grade Two.
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4. The house in that we live is very small.
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5. The sun gives off light and warmth, that makes it possible for plants to grow.
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6. I've read all the books which I borrowed from the library.
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7. This is the best film which I have ever seen.
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8. My father and Mr Smith talked about things and persons who they remembered in the country.
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9. Everything which we saw was of great interest.
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10. His dog, that was now very old, became ill and died.
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