1、形容词；2、keep doing一直做某事；3、keep sb doing让某人一直做某事；4、keepsb from doing sth阻止某人做某事；5、keep in+表示状态的词：keep in good health、keep in danger。
keep例句
1、I go swimming every day in order to keep fit.
我每天游泳以保持健康。
2、You'll need to keep a clear head for your interview.
你面试时需要保持清醒的头脑。
3、I said I'd go just to keep him happy.
我说过我要去只是为了让他高兴。
4、I can't keep up with all the changes.
我并非所有的变化都能跟得上。
5、It is important to keep in touch with the latest research.
及时掌握最新研究情况很重要。