同学你好，该知识点来自沪江网校《中小学金牌新概念英语第三册【升级班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好哦~
while后面可以直接加动词，也可以加句子
while后面直接加动词时,动词形式一般要分为两种情况.
1.如果该动词和主句主语之间为主动关系,则一般用其现在分词形式即Ving.如:While watching TV,I heard a knock at my door.=While (I was) watching TV,I heard a knock at my door.

2.如果该动词和主句主语之间为被动关系时,则用其过去分词形式.如:While beaten by his father,the boy cried.=While (the boy was) beaten by his father,the boy cried.
祝同学学习愉快~