进门前你应先敲门。

You should knock the door before you enter.

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足浴学校：学员们在进行进门练习，程序是先敲门，说明自己是谁，并询问可以进来吗，然后在门边等候“客人”的回答。

Foot massage school: the students are undergoing 'entrance training'. The procedure is to knock first, identify yourself, ask if you could enter, and the wait for the customers' answer by the door.

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雷蒙德和黛布拉仅希望这些人能在进门前偶尔先敲敲门。

Ray and Debra just wish someone would knock once in a while.

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