前者 for 是對于 的意思,it's good for you to stop smoking.戒煙是為你好.
后者 of 是屬性,it's very nice of you to help me.=you're very nice to help me.
能轉(zhuǎn)換成sb is/are +形容詞的 就是 It is+形容詞+of sb to do sth
for是是對于這件事情,修飾的是to stop smoking is good
of是修飾的人.=you're very nice to help me,總不能說help me is
nice吧+to do呢to do 好像沒啥關(guān)系，就是有那么個(gè)意思去做某事對。。來說是。。。的