将下列句子改成否定句：
You are playing the violin.
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He was three.（改为否定句）
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Sally has got a new friend. (改为否定句)
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She has got a knife and fork.
______she ______a knife and fork?（变为一般疑问句）
Yes, she______./No, she______.（做肯定/否定回答）
She ______ ______a knife and fork.（变为否定句）

句型转换。
【小题1】Some men are singing.(变成单数)
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【小题2】I am riding my bike now. (对划线部分提问)
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【小题3】We are sweeping the floor. (变为否定句)
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【小题4】Tom is sad. (变为否定句)
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【小题5】The boy is crying. (变一般疑问句)
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