Don't answer back; it's not polite.是什么意思？

Don't answer back; it's not polite.

不要顶嘴, 这样显得你没教养。

answer

vt.& vi. 答复， 解答， 答辩，适应；n. 回答，答案，反应，足以媲美的人；

例句
Aha! Here at last, the answer to my question.
啊哈，我的问题到这儿终于有了答案。

back

n. 背，背部，背面，反面，后面，后部，（椅子等的）靠

例句
He looked back at the abject, silent girl and repeated his question.
他转过头看着这个噤若寒蝉的女孩，又重复了一遍他的问题。

not

adv. 不，[用以表示否定、否认、拒绝、禁止等]不是，几乎不，未必，没有[用于否定后面的词或短语]；

例句
It became very clear that the incident was not just an aberration, it was not just a single incident.
事实已经很清楚，这件事不是偶发的，它并不是一起孤立的事件。

polite

adj. 有礼貌的，有教养的，文雅的，上流社会的，应酬的，客套的；

例句
She had been surprised at how amiable and polite he had seemed.
看到他如此和蔼可亲、彬彬有礼，她非常惊讶。