I can't be positive about what time it happened.

我说不准这事是什么时间发生的。

《牛津词典》

All these changes happened over a period of time.

所有这些变化都是在一段时间内发生的。

《牛津词典》

The incident happened just after ten o'clock local time.

该事件发生在当地时间刚过10点。

《柯林斯英汉双解大词典》

This time,it happened while he was working on a railroad with men who did rough work and looked rough.

VOA: special.2010.08.01

Suppose you are starting a business with somebody-- it could be at any time in history-- Babylonia or something--this must have happened.

假设你要和某人一起做一笔生意...,可以在任何一个时代...,例如古巴比伦或者其他时代...肯定发生过这种事

耶鲁公开课 - 金融市场课程节选

I find that every time we do our meditation on Thursday, I'm always running to make it, or something happened before I get there, I'm like "Oh my God, meditation!"

我发现每次我们周四,要冥想时，我总是匆匆赶过去，或者是到达之前发生一点事故，我就好像“天哪，要冥想！“

普林斯顿公开课 - 人性课程节选

"Some of the greatest performances of all time happened at Monterey, " Adler tells Renee Montagne.

NPR: The Monterey Pop Festival, 40 Years Later

Perhaps the most sensitive location of all was Gracie Mansion, second only to the police commissioner's residence, if the police commissioner at the time happened to live in the precinct, as some of them did.

WSJ: Back on the Crime Beat

Fortunately, by the time this happened for the second time in my career, I had learned my lesson.

FORBES: 4 Ways to Stay Sane in a Toxic Office