when they will come has no been announce中为什么要加been?

问题描述:

when they will come has no been announce中为什么要加been?

被动

被动形式是: be+动词过去分词
所以此句就是被动形式 been announced
他们什么时候来还没有(被)宣布呢.

百度知道有我. (*^__^*)
满意请采纳,多谢!