It has to be in that sense worked for again and again.

不得不因为这个而再三地奋斗。

耶鲁公开课 - 现代诗歌课程节选

And when he urged him, he accepted."

雅各再三地求他，他才收下了“

耶鲁公开课 - 旧约导论课程节选

This again and again.

这样再三地。

哈佛公开课 - 计算机科学课程节选

Because if anything worked, there would be a solution that would have some value over time and people wouldn't have to be seeking out the newest miracle, getting every little thing they see on TV and the like, and I'll show you some amusing examples of those in the next class.

如果真有用,那就找到了长期有效的解决方法,人们就不会再三地寻找方法了,只要看到电视上有什么小妙招就要尝试,下堂课我会举几个有趣的例子

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选