You smile because you are happy. You smile because it releases those endorphins that bring you extra happiness. You smile at others because it is polite and friendly (and you are glad to see them).
微笑是因为你很快乐。你的微笑会释放出一种激素，会为你带来更多的快乐。对别人微笑是礼貌、友好的表现。
Cordial greetings to the teachers , not the extra polite, which embodies respect for others.
这一句亲切的问候，并非多余的客套，它体现了对他人的尊重。
Cordial greetings to the teachers , not the extra polite, which embodies respect for others.
这一句亲切的问候，并非多余的客套，它体现了对他人的尊重。
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