The bus came after I for about half an hour为什么I后面要填had been waiting?为什么不是had waited?wait不是持续动词吗?

The bus came after I for about half an hour为什么I后面要填had been waiting?为什么不是had waited?wait不是持续动词吗?
The bus came after I for about half an hour
为什么I后面要填had been waiting?
为什么不是had waited?
wait不是持续动词吗?

The bus came after I for about half an hour为什么I后面要填had been waiting?为什么不是had waited?wait不是持续动词吗?
过去完成进行时had been waiting强调一直等到那个时候.had waited只是已经等
持续动词当然可以用于这里了
终止动词不行

have been doing sth 表示过去一段时间一直在做什么事