That we are doing has never been done before.改错
__we are doing has never been done before
has been doing have been done区别
has been doing还是 has done
My brother has never been abroad before
We had never been there before
He has never been abroad before.这里的been是什么
all that can be done has been done
Everything that can be done has been done,___?
Has all that can be done been done?
all that can be done has been done.
America has never been about what can be done for
the children have never done that before改为反义疑问句