过去是的英文：
used to be

the dusty precepts of a bygone era.
过去时代的枯燥戒律。

He's the departed department leader.
他是过去的部门领导。

Over time; due to time
随着时间的过去

Let the dead Bury the dead
往事不重提;一切向前看;过去就让它过去

You ought to let bygones be bygones and not worry about it anymore.
"你应该让过去的事就让它过去,不要再忧虑了。"

He made a lunge at the bully.
他向打手猛扑过去。

It doesn't right past wrongs.
它不会纠正过去的错误。

Horse-drawn trolley was the main vehicle in the past days.
马车过去曾是主要的交通工具。

he hollered, grabbing it for dramatic effect.
说罢一手夺了过去。

In the old days they considered traditional Chinese medicine unscientific.
在过去他们认为中医不科学。

It is used as a reflexive.
它被作为反身代词使用。

That was a balk to us.
那对我们是个挫折。

They help us to be maximal encouraging to us.
他们来帮助我们对我们是个极大的鼓舞。

Already used and therefore unavailable for further use.Used of taxonomic names.
已占用的已经使用因而不能再作他用的。用于分类学名称

Why use wood when you can use plastic?
既然能用塑料，何必非用木料？