It ran through that sequence of instructions, in particular it bound x to the value three, x and then it took x times x, got the value of x multipied by x, which of course is nine, bound that to the value of x, and then it printed out the value, and now it's sitting here waiting for an input.

程序按照指令的顺序去执行的，首先是把x和3这个值进行了绑定，然后把x乘以，得到了x乘以x的值，当然也就是9了，然后把x和这个值进行了绑定，然后显示出这个值，然后就等待输入。

麻省理工公开课 - 计算机科学及编程导论课程节选