The point I wanted to make is that for every node, except the leaves, the leaves are the bottom of a tree in this case, are weird, right, they draw trees where the root is at the top, and the leaves are at the bottom.

你没必要看到整棵树，我想说的重点是,对每个节点来说，除了叶子节点,叶子节点指的是树的最下面的节点，电脑科学家都很奇怪,他们画树的时候根是在最上面的。

麻省理工公开课 - 计算机科学及编程导论课程节选

But sometimes it's necessary when you have really big course load

但是有时候课程量很大的时候这是必要的，

开放式的课程？ - SpeakingMax英语口语达人

Well, you don't have to just take what you've been handed round in life, functions like print F or round or maybe other functions you've seen in super sections or by poking around.

好的，你没必要把传给你的参数保存起来,像函数printf或者,或者你们看到的其他的函数,在超级课程中或闲逛的时候。

哈佛公开课 - 计算机科学课程节选