通配符在类型系统中的作用部分来自其不会发生协变（covariant）这一特性。

The utility of wildcards in the type system comes partially from the fact that generic types are not covariant.

youdao

在这篇文章中清晰信号的作用部分，当你不使用食物或玩具帮助狗儿出任动作时，我会详细说明身体作用信号的用法。

For the purpose of clear communication in this article I will define a signal as the use of your body when your not using food or a toy to help a dog perform a behavior.

youdao

现在，我们不想给你留下这样一种印象，即这三个组成部分总是完美地结合在一起，共同作用。

Now, we don't want to leave you with the impression that these three components always work together perfectly.

youdao

Even though the signs of the enthalpy changed, and the signs of the entropy changed because it's a combination of the two that matters.

即使自由焓的符号发生变化，熵的符号也会发生变化,因为这两部分都起作用。

麻省理工公开课 - 热力学与动力学课程节选

Part of the problem with using operant conditioning with babies is it's difficult to get them to behave in any systematic way.

应用操作性条件作用的部分问题在于,很难使婴儿们按照系统的方式行动

耶鲁公开课 - 心理学导论课程节选

So we can think about something I mentioned last time, which is when we're thinking about chemistry and what's really interesting in terms of chemical reactions, it's mostly valence electrons we're talking about, those are the ones that tend to be involved in chemical reactions.

我们可以考虑一下我上次提到过的一件事，那就是如果我们讨论化学,以及什么是化学反应中,真正令人感兴趣的东西，我们讨论的几乎都是价电子，它们才是在化学反应中,真正起作用的部分。

麻省理工公开课 - 化学原理课程节选