In other experiments, Provine has proved that yawning has nothing to do with oxygen or carbon dioxide intake.

在其他的实验中，普罗万也证明打哈欠与氧气或者二氧化碳的吸入没有关系。

According to a classic study of laughter by Robert Provine of the University of Maryland, Baltimore County, and his colleagues, laughter is an unexpectedly serious business.

美国巴尔的摩马里兰大学的罗伯特·普鲁文斯和他的同事做过一项典型的研究。根据他的研究，笑是一件极其严肃的事情。