How often do you brush your teeth?

你多久刷一次牙？

《柯林斯英汉双解大词典》

You must brush your teeth everyday.

你必须每天刷牙。

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You need to brush your teeth after sweets.

你吃完甜点之后要刷牙。

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"If you don't brush your teeth you're going to lose them, " Mr. Smith warns them.

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Ever notice how you brush your teeth every morning and evening?

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They can tell you how many pounds it takes to--of force it takes to brush your teeth, you know.

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