i stopped to listen,and my son seemed(to be enjoying)himself shut in the living room为什么要用be?

问题描述:

i stopped to listen,and my son seemed(to be enjoying)himself shut in the living room为什么要用be?

seem to do/be 介词to后面需要用的是动词的原形,这里动词就是系动词be

后面enjoying
当然不能前面直接用to
进行时这里表示正在