造句。

1. she, the window, open, now. (用现在进行时连词成句)

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2. is, who, the window, cleaning? (连词成句)

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3. She is closing the door now. (改成否定句)

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4. You are doing your homework. (用"I"作主语改写句子)

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5. they, the tree, sing, now, under. (用现在进行时连词成句)

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循环气流动造成的压力降等于（）。