And in fact, one of the lessons you may already be realizing with P sets is that things seem to take twice, three times, four times longer than you actually might think.

从习题集中你可能已经得出的一个教训就是,程序所花的实际时间往往是你开始以为的两倍，三倍，四倍甚至更长。

哈佛公开课 - 计算机科学课程节选

and then you also have the smaller, you know like, three or four-story homes which one family may occupy.

然后你也有那种小一些的，只有三四层楼的，一个家庭就可以占据的房子。

上东区的氛围 - SpeakingMax英语口语达人

Americans spend the most time out of any other people in the world volunteering in average four hours a week, volunteering outside their job which may also have a social objective more than any other people in the world.

比其他任何人所花的时间都多,平均每周有四个小时做志愿者的工作，做与自身工作无关的善事,他们比世界上其他人更具社会目标。

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So in other words, if you terminate these lines early, if you terminate the four loop early, if you terminate an if condition early with that semicolon, the code may very well work; and this is a common source -- of frustration and conundrum because you don't -- because your code looks right and yet it's misbehaving, but that semicolon means stop looking for subsequent lines of related code.

换句话说，如果你用分号过早的终止了这些代码行，如果你过早地终止了那个for循环，如果如此,一个if条件，代码可能可以运行，这就是,挫折和问题产生的源头，因为你没有-,因为你的代码看起来是正确的，但是运行是错误的，那个分号的意思是,停止寻找后面相关的代码。

哈佛公开课 - 计算机科学课程节选

As you may know, there's yet another organization where we could group this in units of four but for all intents and purposes-- there are a few nuances to it-- four is simply a multiplication of two.

也许你知道的,还有另外一种组织方式,我们可以四拍一组,但是不论出于什么动机或者目的,这其中的区别甚微,四拍就是两拍的简单相乘

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