And b, they have what's called a low expense ratio since they're easy to implement, you don't pay anyone to be brilliant to implement if for you.

但是他们的费用比率很低,因为这种做法很容易，你不需要,有多聪明就能去实施。

麻省理工公开课 - 计算机科学及编程导论课程节选

Every time a product shows up it's bought and paid for, for the most part.

产品的每次出现都需要支付费用,在大多数情况下都是这样

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

So, then we had to select our fare.

然后我们需要选择我们的费用。

哈佛公开课 - 计算机科学课程节选