were后为什么还可以加being?The windows and doors came from old buildings around the town that were being pulled down.
问题描述：
were后为什么还可以加being?
The windows and doors came from old buildings around the town that were being pulled down.
答
be在这里已经不是作为系动词了 它和后面一个单词组成正在被…
答
这里是过去将来时，WERE用过去式，BEING 用现在进行时表将来
答
就是过去进行时,be doing,这里是被动关系,所以是were being done