The vast overwhelming majority of people needed to farm land, in order to stay alive.

当时古希腊拥有众多的人口,人们需要农田才能生存

耶鲁公开课 - 古希腊历史简介课程节选

Then you really won't be able to afford to stay alive.

说不定你连活下去都很困难

耶鲁公开课 - 金融市场课程节选

in spite of the fact that we take a variety of chemicals into our bodies in different ways and we have to do that to stay alive, but we have mechanisms to control this very well.

尽管事实是我们从不同途径,摄入各种化学物质以维持生存,但我们能够很好地控制它们在体内的总量

耶鲁公开课 - 生物医学工程探索课程节选