老师好，一下是今天遇到的一个不太理解的句子：

  Another good example of the separation of powers is the process by which a person becomes a Supreme Court justice.

我理解的这句话要表达的意思是：另一个可以体现三权分立的很好的例子是成为最高法法官的流程。

如果让我写的话，就会变成这样：Another good example of the separation of powers is the process how a person becomes a Supreme Court justice.或者the process that a person becomes a Supreme Court justice.

不明白这个by是要表达什么意思。

先谢谢老师，希望老师同时能告诉我要补补哪里。