"for" 是一个 介词，它后面通常跟的是 带有名词属性的词。这些词可以是名词、代词、动名词（V-ing形式）或动名词短语。例如：
1. She bought a gift for her friend.
2. They are playing football for the team.
3. I have been studying English for five years.
4. The trip will take us for two days.
此外，"for" 也可以表示时间、距离、数量等，例如：
1. We need to prepare for the meeting.
2. The book is written for young adults.
3. They traveled for thousands of miles.
当 "for" 作为连词时，后面跟的是一个句子，表示理由或原因，例如：
1. I stayed at home for the entire weekend.
2. She didn't come because of the weather.
总结来说，"for" 作为介词时，后面跟的是名词或名词性短语；作为连词时，后面跟的是句子。