And the fourth thing to notice is, I've used abstraction. I've said nothing about how I'm going to make square root.

第四件事情就是，我运用了抽象,我对怎么去求平方根没有提及。

麻省理工公开课 - 计算机科学及编程导论课程节选

All right. The fourth thing I'm going to do, is I'm going to then construct the block of code.

好，我要做的第四件事情就是，我会去写这块循环代码。

麻省理工公开课 - 计算机科学及编程导论课程节选

And step four is going to have us figure out how many bonding electrons we have, so we have 16 minus 10, is going to be 6 bonding electrons.

而第四步需要判断,我们有多少个成键电子，那么我们有十六减十，也就是六个成键电子。

麻省理工公开课 - 化学原理课程节选

So in the fourth stanza we as readers have no idea where we are or when it is the speaker of the poem imagines himself to be speaking, and it's at this point that something quite strange happens.

所以作为读者，对第四段我们不知道,自己在哪，诗的代言者在哪,什么时候想说话，而且就是在这时非常奇怪的事情发生了。

耶鲁公开课 - 弥尔顿课程节选