根据所给的句子，仿照例句用must或mustn't造句。
e.g. Never swim in the waterfall.
You mustn't swim in the waterfall.
1. Never speak loudly in the library.
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2. Never sleep outside at night in winter.
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3. Don't play with fire.
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4. Always do warm-up exercises before running.
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5. Always wear sports shoes on Sports Day.
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