So the idea behind valence bond theory is very easy to understand.

价电子成键理论,非常容易理解。

麻省理工公开课 - 化学原理课程节选

Well in C and other languages that we'll see this semester, you use what's called the for loop, and this as syntax isn't quite as straightforward but once you know what to look for, it's very easy to understand.

在C语言和一些我们这学期将要接触的编程语言中，你将会用到所谓的for循环，也许作为一种语法规则，它看起来不是那么的通俗易懂,但是你一旦知道曲中奥妙，就不难理解了。

哈佛公开课 - 计算机科学课程节选