keep表一直什麼詞性

是動詞詞性，例如：

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.你面試時需要保持清醒的頭腦。

3、I said I'd go just to keep him happy.我説過我要去只是為了讓他高興。

4、It is important to keep in touch with the latest research.及時掌握最新研究情況很重要。