And they're awfully simple because, all I can do now, is decide whether to execute some piece of code or another.

它们之所以太简单的原因是：,现在我能做的，就是,决定执行一块代码或者执行另外一块。

麻省理工公开课 - 计算机科学及编程导论课程节选

- So double bar means if this condition or this one -- and maybe even both -- are true, go down this road and execute that code.

所以复纵线意思是，如果这两个条件之一-,或者两个都--是成立的，那就继续,执行后面的代码。

哈佛公开课 - 计算机科学课程节选

And what it's saying semantically is, using that variable as my placeholder, have it walk through this collection, starting at the first thing, execute that code, then the next thing, execute that code, and so on.

它的语义意思就是，把这个变量应用为我的占位符，用它来遍历这个集合，从第一个元素开始，执行代码，然后下一个元素，再执行代码。

麻省理工公开课 - 计算机科学及编程导论课程节选

So conceptually the key difference here, besides the syntax looking slightly different, it just means that if you want a chunk of code to execute no matter what initially, ; you can use the do while loop; if you want to check a condition first, you can use the while loop.

所以概念上，则关键的区别是，除了语法看起来有点不同，它的意思是如果你想要一段代码,最初无论如何都要执行，你就可以用do，while循环;,如果你想要先检查条件，你可以用while循环。

哈佛公开课 - 计算机科学课程节选

As an aside, if you ever just have one line of code that you want to execute, one puzzle piece in Scratch terminology, ; you actually don't need the curly braces; you only need the curly braces if you have two or more lines of code that you want to execute if that condition is true.

此外，如果你只有一行代码,需要执行，在Scratch，术语中叫做,一句代码，你就不需要使用花括号了;,如果那个条件成立，你有两行或更多行的代码时需要执行时,你就需要花括号。

哈佛公开课 - 计算机科学课程节选