句型转换。

1. It's time for supper. (同义句)

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2. She is often late for school. (反义句)

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3. We are learning to fly a kite. (对划线部分提问)

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4. I think you want to go home. (否定句)

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5. Lucy, do your homework. (用now改句)

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如图，长为L的不可伸长的细线，拴一质量为m的小球，一端固定于O点，让其在水平面内做匀速圆周运动(这种运动通常称为圆锥摆运动)，如图所示。当摆线L与竖直方向的夹角是α时，求：

(1)线的拉力F；

(2)小球运动的周期。