The code in Listing 1 is fairly straightforward; we've simply chained together multiple exceptions to create a single, nested exception.
清单1中的代码很简单；我们已经简单地将多个异常“串”在一起，以创建单个、嵌套的异常。
2
You embed objects within other objects to form nested HTML code.
在其他对象中嵌套对象以构成嵌套的HTML代码。
3
Your code should (almost) never have multiple nested loops (a loop inside a loop inside a loop). Most of the code written today should use Hashtables, simple lists and singly nested loops.