您可能需要一个根本不执行任何工作的活动，例如，当您拥有一个需要某个活动的构造，但没有要执行的任何工作时。

You might need an activity that does nothing at all, such as when you have a construction that requires an activity, but there is no work to be done.

youdao

此队列跟踪要执行哪些服务请求。

This queue keeps track of which service requests to execute.

youdao

要执行IPD，必须生成特定的工件。

To execute IPD, certain artifacts must be generated.

youdao

So the open curly brace followed by the closed curly brace means everything inside of these curly braces should get executed, but only if that first condition is actually true.

所以左花括号后面跟着,右花括号，这意味着花括号里面所有的代码,都应该是要被执行的，但只有当第一个条件是正确的。

哈佛公开课 - 计算机科学课程节选

So what we would see, I'm going to completely fake this, is a program that operates like that.

所以我们会看到，我要完全掩盖这一点，就好像程序真的是那样执行的。

哈佛公开课 - 计算机科学课程节选

Which is a way of reminding you that I need to think as I write the code about what are my expectations from the input, and how might I enforce them.

通过这个我在提醒大家,在写代码的时候,要搞清楚对输入的期望，并思考下如何执行这些期望。

麻省理工公开课 - 计算机科学及编程导论课程节选