1、不定式：用于即将发生的动作或者即将出现的状态；不定式可以充当定语（The test to take is going to be very difficult.）、主语（To work with him is a pleasure for me.）等.
2、动名词：只能用于主语、宾语、表语、定语等,不能充当任何状语（如时状、地状）.例句：I want to take the sleeping berth.Sleeping is essential for everybody.I like jogging.
3、分词：现在分词表示正在发生的事情,过去分词表示已经发生或者被动的含义.The sleeping baby looks lovely./ The guests invited are all the managers./ The windows cleaned are shiny.