You used to be able to see the church from here.
Nobody had ever heard of it.
I have read the book before.
- 因为以前见过他， 所以我立刻就认出他来。
Having met him before, I recognized him at once.
Formerly this building was a hospital.
You will have heard this story before.
People used to think that only humans could use language.
It used to be thought that the earth was flat.
It was believed that the earth was flat.
Johny was a chemist; now Johny is no more. For what he thought was water, was H2SO4.