They were so busy talking with each other that they forgot the time怎么解释?为什么so后面是动词的ing形式啊?

分类: 作业答案 • 2021-12-20 02:51:56

问题描述：

They were so busy talking with each other that they forgot the time怎么解释?
为什么so后面是动词的ing形式啊?

答

这里用了固定短语 be busy doing sth 忙于做某事