It's very friendly __ him to help me when I'm in trouble.

问题描述:

It's very friendly __ him to help me when I'm in trouble.
A.for B.to C.of D.with
选什么?请问理由?
选for还是of?

选C.of 是表示某人具有什么样的品质的,其他几个介词无此词义.