I'm sure that laughter has been selected by evolution as a useful device for promoting social communication.

我想进化肯定选择了笑作为促进社会交往的有用工具。

youdao

Laughter has been shown to relieve stress, stimulate blood flow, relax muscles, promote a healthy immune system and relieve pain.

笑声会释放压力，加速血液循环，放松肌肉，提升强健的免疫系统，缓解疼痛。

youdao

The laughter finding makes a great deal of sense, and laughter has been described as more like a different way of breathing than a way of speaking.

笑的作用，非常有意义，与语言表达方式相比，笑更多地被描述为一种不同的呼吸方式。

youdao

You may have noticed, if you look outside, that the cloud of uncertainty -- (laughter) -- has been lifted over our economy, or almost, anyway.

WHITEHOUSE: Press Briefing

He looks pretty real to me. (Laughter.) I wasn't imagining him up here talking, was I? (Laughter.) He has been in the wind energy business for nearly 20 years.

WHITEHOUSE: Remarks by the President at Campaign Event

Now, I want to thank K Neal for having us here today, giving us a quick tour and having us look at all these -- all these trucks. (Laughter.) This is a business that has been selling commercial trucks for over 40 years.

WHITEHOUSE: President Obama on the May Jobs Numbers