It is good manners to do... ……是礼貌的表现
例句：
It is good manners to stop talking when you are eating dinner.
吃饭不说话是有礼貌的表现。
It is good manners to take off your shoes before you enter a house.
进屋前脱下鞋子是有礼貌的表现。
A:Don't you know it is good manners to stare one's eyes when he is speaking?
难道你不知道当别人说话时看着别人的眼睛是一种礼貌吗？
B:Sorry, my mother didn't tell me.
对不起，我妈妈没有告诉我。