You can call your broker and say, I'd like to short stock number one and what the broker will do is borrow the shares on your behalf and sell them and then you own negative shares.

你可以打电话给你的经纪人说，我要做空一号股票,经纪人就会在你的名下赊入这些股票,然后卖掉,这样你就拥有数量为负的股票了。

耶鲁公开课 - 金融市场课程节选

It's reasonable because it's meant TMP for temporary purposes just to call it temp or T-M-P for short, X and I can define temp as -- why don't I set it as equal to X, initially, because now that I've stored X in a separate chunk of memory, I can now change its value and then I can say Y gets, not X, but temp, and so now I've actually swapped these values.

这是合理的，因为它是为,暂时的目的，只要叫它Temp或简称它为，我可以定义temp为--为什么我不把它设定为等于，最初的，因为现在我把X存储在一个单独的内存块中,我现在可以改变它的值，然后我说Y等于，不是X，而是temp，所以现在我交换这些值。

哈佛公开课 - 计算机科学课程节选