And now, if I'm touching mouse pointer, we saw that Boolean expression before, play sound meow, wait a couple of seconds, and then just keep checking.

现在，如果我们碰下鼠标指针，起初我们看到一个布尔表达式，播放猫叫的声音，等几秒钟，然后如刚才那样做检测。

哈佛公开课 - 计算机科学课程节选

Scratch This Boolean expression allows you to say to scratch if you are touching the mouse pointer, the little arrow, do something. How do we do something?

布尔表达式允许你告诉,当你触碰到鼠标指针，也就是小箭头，程序就相应地做一些事情？

哈佛公开课 - 计算机科学课程节选