It is polite you to give seats to the elderly.A. withB. forC. ofD. to

问题补充：

It is polite you to give seats to the elderly.

A. with

B. for

C. of

D. to

答案：

A. with

B. for

(答案→)C. of

D. to

解析：考查固定句型。It is +adj. for/ of sb. to do sth.“做某事对某人来说......”，当句型中的形容词指人的品质时，用介词of，其它用for。Polite指人的品质，故用of。句意“给老人让座，你真是太有礼貌了。”故选C。