For the carbon, we start with 4 valence electrons, we have 0 lone pair electrons minus 4, and we end up with a formal charge of 0.

对于碳，我们从四个价电子开始，我们有零个孤对电子，再减去四，最终我们有零个形式电荷。

麻省理工公开课 - 化学原理课程节选

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

They have breakfast, they drink, and they advance typically to a battle song called the paeon which we have, what they sang.

他们吃早餐,喝酒,随即开始唱战歌,一种四音节的歌曲

耶鲁公开课 - 古希腊历史简介课程节选

What have we done over the last three or four lectures? We've started introducing you to classes of algorithms. Things that I'd like you to be able to see are how to do some simple complexity analysis.

我们在过去三节或四节课中讲了什么？,我开始向你们,介绍算法的类型,我想你们知道的是,如何做一些简单的复杂度分析。

麻省理工公开课 - 计算机科学及编程导论课程节选

So in our first structure, we would find for the nitrogen we have a formal charge 5 minus 4 minus 2, because we're starting with 5 valence electrons, so that is a formal charge of minus 1.

那么在我们的第一个结构中，我们发现氮的形式电荷量是五减去四4,再减去二，因为我们开始有五个价电子，因此它的形式电荷量是负一。

麻省理工公开课 - 化学原理课程节选

For decades, ever since the mile was timed, no one broke the four minute barrier.

数十年来，自从开始一英里跑计时以来，没有人突破四分钟界限。

哈佛公开课 - 幸福课课程节选

After decades of relatively unspectacular growth, compared to the east Asian economies, India's economy suddenly took off three or four years ago, growing at 8% or more a year.

经历了几十年的相对高速发展后，与其他东亚经济体相比，印度经济三或四年前突然开始腾飞,以每年8%甚至超过%,8%的速度增长。

普林斯顿公开课 - 国际座谈会课程节选

Lloyds of London, which now does things like ensure quarterbacks' knees and things 685 00:36:00,852 --> 00:36:02,973 but it begins in the eighteenth century when people go into the docks.

伦敦的劳埃德市场,现在做一些,为四分卫的膝盖保险之类的事不过他们早在在十八世纪,航运业刚兴起时就开始做保险了

耶鲁公开课 - 欧洲文明课程节选

They start next Thursday in the cycle.

从下周四开始循环

耶鲁公开课 - 聆听音乐课程节选

In the early days when there are four or five formulas, you could memorize all of them and you can try each one of them until something works, but after a couple of weeks you will have a hundred formulas and you cannot memorize all of them.

刚开始我们只会涉及到四,五个公式,你可以全部记下来,你可以一个一个试,直到解出答案,但过了几个星期,你就已经学了一百多个公式了,你没法全部记下来

耶鲁公开课 - 基础物理课程节选

And what you will give me in return is on the first day, one cent-- one penny; on the second day, two cents; third day, 4 cents... Every day, twice as much as the previous day, starting with one.

你们给我的是，第一天，一分钱;,第二天，二分钱，第三天，四分钱。,每天给我前一天的两倍钱，从一分钱开始。

哈佛公开课 - 幸福课课程节选

And runners proved the doctors and scientists-- proved that they were right and ran the mile in two seconds and 4 minutes, one second, but no runner could run the mile in under 4 minutes, ever since the mile was actually timed-- when they started to time runs.

跑手们证明了医生和科学家…,证明了他们是对的,一英里跑四分钟两秒，四分钟一秒，但没有跑手能少于四分钟，从一英里跑计时以来-,当人们开始计时跑时。

哈佛公开课 - 幸福课课程节选