So, the process of developing a vaccine occurred over a long period of time.

疫苗的发展经历了很长一段时间

耶鲁公开课 - 生物医学工程探索课程节选

Now,that has changed, for sure; but,the centralization of the French government and the domination of Paris over the life of the nation is very difficult to change, over a long period of time.

现在,情况已经发生了改变,但是法国政府的中央集权化,以及巴黎在国民生活中的支配地位,在相当时间段内,都很难得以改变

耶鲁公开课 - 1871年后的法国课程节选

Even if you imagine that slaves did the work, you would need a hell of a lot of them, over a long period of time, and you had to feed them, if nothing else.

哪怕你想象这个墓穴是由奴隶所建造,那也一定是成千上万的奴隶,经过了相当长的时间工作,至少,你还要养活这些奴隶

耶鲁公开课 - 古希腊历史简介课程节选

It might bend and bow, that is it's not the forces of nature like the movement of the river that's knocking the bridge down, but it's just the failure of these materials over time, that they don't last as long as they might.

这桥可能会折断,不一定是洪水这样的自然灾害,导致了桥梁的坍塌,可能只是因为建桥的材料老化,这种材料没有那么持久耐用

耶鲁公开课 - 生物医学工程探索课程节选