头脑清醒

Mountaineering is dangerous, so you need to keep your wits about you.

登山是危险的运动，你必须时刻头。

A whiff of fresh air cleared his head.

他吸了一点新鲜空气后头了。

If a marriage is to work, both partners must go into it with their eyes open.

如果姻美满，那么在步入姻堂的时候两个人都得头，知道姻意味着什么。