So if I want to use a string as we'll call it which is a word or phrase generally, they always go between double quotes, David hence the quotes around David, and they are double quotes not single quotes intentionally.

当我们要表示单词啊，词组啊，句子啊等等这样的东西时,就会用到字符串，它们位于双引号之间，也就是这里双引号之间的，是双引号，不是单引号哦。

哈佛公开课 - 计算机科学课程节选

always to use a black cab driver because we know where we are going,

一定要乘坐黑色出租车司机的车，因为我们知道我们要去哪儿，

小心微型出租车 - SpeakingMax英语口语达人

So just in case I happen to use the CS50 library, we've configured the cloud in such a way that make just always provides you with access to it.

所以万一我碰巧使用了CS50程序库，我们用这种方法配置了联网,那样我们就有使用它的权利了。

哈佛公开课 - 计算机科学课程节选

But in the real world when dealing with humans, but even when dealing with animals, we don't actually always use primary reinforcers or negative reinforcers.

但当我们在现实中训练人类，甚至是训练动物时，我们实际上并不总是用到初级强化物,或是负强化物。

耶鲁公开课 - 心理学导论课程节选