It used to be the case-- I forget how long drive-in windows have been around, certainly as long as you guys can remember-- but there was a time when drive-in windows didn't exist.

曾经是这样的情况,我忘了免下车餐厅已经出现多久了,当然可能自打你们记事时就出现了,但是在免下车餐厅尚未出现的时候

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

I need to know how long, so that I can let my roommates know.

我得知道大概有多久，这样我就可以告诉我的室友们了。

How long实战 - SpeakingMax英语口语达人