You have to test it by giving the vaccine to a large population of people, and then watching and seeing if you've reduced the incidence of the disease.

这样的测试的做法只能是,给大量人群分发疫苗,接着观察和了解,这种疾病的发病率是否有所降低

耶鲁公开课 - 生物医学工程探索课程节选

You're not intervening with people, you're observing usually large numbers of people in a population.

不干涉他人生活,只是观察一个人群中的许多个体

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Northern Italy has a large percentage of the population who are middle class.

意大利北部有很大比例的中产阶级

耶鲁公开课 - 欧洲文明课程节选

That explains, in large part, why there was such a decline in population, why the Dark Ages were so dark, lots of poverty, lots of starvation, but also, as I suggested when I spoke of this earlier, also the freedom if you could make it, to learn and also to grow stronger.

这解释了,在绝大部分地区,为什么存在着这一类的人口消减,为什么黑暗时代如此黑暗,如此贫困,如此多的饥荒,但是同时,就如在我之前所提到的,同样可以,如果做得到的话,去学习以及使自身强大

耶鲁公开课 - 古希腊历史简介课程节选