Make sure that your tongue touches the back of the lower teeth.

一定要使你的舌头接触下齿的背面.

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Faulty contact between the upper lower teeth when the jaw is closed.

转动时齿轮上的齿与齿相啮合.

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Please move the brush downwards on the upper teeth and upwards on the lower teeth.

刷上颌时牙刷应向下移动,刷下颌时牙刷应向上移动.

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