For the most basic, most common, most frustrating part of being a patient.

这是作为一个病人最基本，最常见， 却也最令人无奈的地方。

An outlier is someone who is not common, not part of the common group, okay?

离群值是不常见的人， 不属于普通群体的人， 好吗？

Idioms are a very common part of the English language and I'm sure I don't need to tell you that they're challenging to learn and use.

习语是英语中非常常见的一部分，我敢肯定我不需要再告诉你们学习和使用它们是有些挑战的。

But they are a very common part of American college life; you can't go to an American university – a large university and not be aware of or see these Greek organizations, as they're called, on campus.

但它们是美国大学生活中非常普遍的一部分；你不可能去一所美国大学——一所大型大学， 而不知道或看到这些希腊组织， 正如他们所说的那样， 在校园里。

Sweeteners have become such a common part of our diet that environmental scientists have started looking for traces of them — particularly acesulfame potassium, which passes through the body largely undigested — as a marker for human waste in lakes and rivers.

甜味剂已经成为我们饮食中普遍存在的成分，以至于环境科学家开始寻找它们的痕迹，特别是钾型甜味剂，因为这种成分在经过消化后基本上不会被吸收，所以可以作为检测湖泊和河流中人类废物的标志。