decide 与 decided

1.decide（决定）后面接不定式或on（或upon）和动名词，如I have decided to help him和I have decided (up)on helping him，用不定式普通些。有时也接以that引导的从句。例如：I decided that I would help him.用that引导的从句里往往用should或虚拟现在式。例如：We (have) decided that the meeting (should) be held on Saturday evening.

2.说“决定…”该用decide on（或upon），不该只用decide，如I have decided on（或upon）a course of action里的on或upon不可省去。但I have not yet decided on（或upon）where to spend my holidays里的on或upon在口语里往往省去。

3.用decide很容易犯双重被动的错误，如不可说He has been decided to be helped，该改作It has been decided to help him或It has been decided that he should be helped。

4.a decided man（一个果断的男子）里的decided是不及物动词decide的过去分词用作形容词。

5.参见：decisive 的用法及固定搭配