曾经用英语可以表示为ever，once，used to do sth.等。例句：People used to think the earth was flat.人们曾经认为地球是平的。
ever，once，used to do sth.
People used to think the earth was flat.
Some birds which were once a common sight are now becoming rare.
It was once thought that lead could be transmuted into gold.
It was once thought that the sun travelled around the earth.
I used to collect stamps.
Had Jamie ever been in any kind of trouble?
Godfrey had been friendly to me.
I have been moved to write a few lines of verse.
Politics used to be the privilege of the property-owning classes.
It was evident that she had once been a beauty.