Clowns have a real purpose: to make people laugh.

VOA: special.2009.01.11

The laugh is a lot like the "wow." It's that sound you make just because you're experiencing something, just because you're having a response to what's in front of you, something someone says.

这笑声很像“哇“这个字，是一种,因为正在经历某些事而发出的一种声音，作为你对面前发生的事或是，一些人说的话的反应。

耶鲁公开课 - 1945年后的美国小说课程节选

One group of children was a control group; the second group was taught to think back to experience that make them laugh or smile.

一群小孩组成对照组;,有人教第二组小孩回想,让他们大笑或微笑的经历。

哈佛公开课 - 幸福课课程节选

He could make people laugh without saying a word.

VOA: special.2009.07.19

When monkeys get together to kill and eat somebody they make a kind of a laughing noise and chimpanzees laugh when they tickle each other.

猴子一起猎杀其他动物时,它们会发生出一种笑声,黑猩猩胳肢时也会笑。

耶鲁公开课 - 心理学导论课程节选