It's never--it probably wasn't quite that easy but the invading side goes for something that the other side will have to defend and that determines when the fighting takes place.

可能不会这么简单,但当入侵方为了某一目进行侵略,被侵方就不得不防守,这就决定了战争的爆发时间

耶鲁公开课 - 古希腊历史简介课程节选

Restriction enzymes have names, The names all look - they're all italicized and they're capital letters and small letters so that they won't be easy for you to understand, but they are - if you know the nomenclature, easy to understand.

限制性内切酶有自己的名字,名字看起来都很--,都是斜体的,大写小写字母混合,你们不太容易理解,但它们都是--如果你懂命名法,是很容易理解的

耶鲁公开课 - 生物医学工程探索课程节选

So, if you're looking back, say, from the end of the nineteenth century, it's not easy to see, but you can see these-- don't ever think that history runs on railroad tracks, and all you need is the timetable to show when modernization shows up.

所以,当你回顾历史,从十九世纪的末尾开始,虽然不太容易,但还是可以看出...,别以为历史是在固定轨道上行进的,别以为你只用拿时刻表,就知道新时代什么时候来临

耶鲁公开课 - 欧洲文明课程节选