第1个回答 2016-11-14
It's polite for us to help others.
我们帮助别人是很有教养的。
第2个回答 2016-11-14
It is polite for the students to greet their teachers first when they meet each other.
对学生来说,，碰到老师时，先跟老师打招呼是礼貌的（行为）。
第3个回答 2016-11-14
It's polite for the young to say hello to the old .本回答被提问者采纳