Their astronomers had discovered that at a certain time of year the brightest star, Sirius, would disappear.

他们的天文学家发现，在一年中的某个时候，最亮的天狼星会消失。

youdao

youdao

A driver takes the minibus to a certain place at a certain time, so people know when to expect it.

司机会在特定的时间开小型巴士去特定的地方，所以人们知道什么时候会有小型巴士来。

youdao

"The bus went into the middle of the desert and at a certain moment the call to prayer came just lilting through the desert - first time I've ever heard it - and then the bus stopped and all of those colorful people got off the bus."

VOA: standard.2010.05.21

Each year it's dramatized by the cycle of the seasons, And at a certain time of the year it seems that The forces of darkness and chaos are prevailing but each spring, Once again, cosmic order and life return.

每年这冲突都由季节的轮回戏剧性地体现出来，仿佛是每年都有一个时期,弥散着黑暗和混乱的势力，可是每当春天来临，宇庙的秩序又恢复了。

耶鲁公开课 - 旧约导论课程节选

And they have to put in a certain amount of work time, working at the Food Co-op.

他们得抽出一部分时间去食品供销社工作。

布鲁克林的变化 - SpeakingMax英语口语达人

Shareholders, unlike bondholders, receive no legal promise to be repaid in cash at a certain time.

ECONOMIST: Stocks in trade | The

You know, I made a mistake, and at a certain time, it came time to pay for it, and I paid for it.

FORBES: Forget Oprah: James Frey Talks Truth With Big Think

Arguably, archived email, handled the right way, could perform the same function, essentially, a certification that a document was created at a certain time and has not been altered.

FORBES: After The Post Office