Don't arrive late for class. You must be on time.

上课不要迟到。你必须准时上课。

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You must be there on time.

你务必要按时到达那里。

《新英汉大辞典》

On some operating systems, there is a strict limit on the number of images you can have at any one time, so you must be aware of this restriction when using them.

在某些操作系统上，对任一时间内可拥有图像的数量有严格限制，因此使用它们时必须注意这一限制。

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As appealing as these promotions are, you must be able to pay on time.

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You must be wasting your time on something less interesting and fruitful.

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You must have the time and resources to be able to work on your response, in the form of another implementation.

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