So what we'll have here is a trigonal planar case, and you can see that we only have three electrons that are set for bonding, so we'll add three hydrogens, and for b h 3, we'll get a stable structure here.

让电子劲量远离的时候，不用考虑它,这个例子是平面三角形，你可以看到，只有3个电子可以成键。

麻省理工公开课 - 化学原理课程节选

Why do you need three doses of Hepatitis B?

为什么你需要三支重组乙肝疫苗呢

耶鲁公开课 - 生物医学工程探索课程节选

I've got one test, I've got a subtraction, I've got a multiplication, that's three steps, plus whatever number of steps it takes to solve a problem of size b minus 1.

我进行了一次比较，一次减法，一次乘法，一共是三个步骤,再加上t的步骤数。

麻省理工公开课 - 计算机科学及编程导论课程节选

A to B is one distance, which is a large one, and B to C is only half that distance, and that's because of the way the Greeks laid this thing out with their two to one ratios, three to two ratios and so on.

到B是一个距离,比较大,而B到C只有半个距离,因为希腊人,用诸如二比一,三比二,之类的频率比来安排音阶

耶鲁公开课 - 聆听音乐课程节选

b times. So I've got to go 3 b steps. All right I've got to go through the loop b times I've got three steps each time, and then when I pop out of the loop, I've got two more steps. All right I've got the initiation of answer and the return of it.

好，我一共执行了b次循环,每次循环内部进行了三次基本操作,当跳出循环后还有两个基本操作，因此这个初始的答案就是,2+3b次基本操作,来完成这个循环。

麻省理工公开课 - 计算机科学及编程导论课程节选