Yawning may help you keep a cool head-literally, a new study suggests.

打哈欠也许可以帮你保持头脑清醒——一项新的研究如是说。

youdao

Yawning may help you keep a cool head-literally, a new study suggests.

打哈欠也许可以帮你保持头脑清醒——一项新的研究如是说。

youdao