of是介詞，一般后接名詞，代詞或動名詞。for同樣是介詞，后接名詞，代詞或動名詞。意義多為“為了”。
1、Would you say what you felt was a feeling of betrayal?
你是否覺得有一種被人出賣的感覺？
2、A flock of birds flew towards us slowly from far away.
一群鳥兒從遠處朝我們緩緩飛來。
3、We could all do with a cup of tea .
要是能給我們都來杯茶就好了。
4、Isn't that enough for you?
那對你來說不夠嗎？
5、I knew he worked for a security firm.
我知道他在一家保安公司工作。
6、She appears nightly on the television news, speaking for the State Department.
她作為國務院的發言人，每晚都會出現在電視新聞中。