keep a clear [cool] head; keep sober-minded; 保持清醒的头脑
The lessons learned at the cost of blood helped to sober us. 血的教训使我们的头脑清醒了。
He was perfectly sane when he committed the crime. 他犯罪时,神志十分清醒。
He apologized when he sobered up. 他清醒过来后表示道歉。
牛津高阶第八版
美国韦氏词典
Dictionary.com
Free Dictionary
维基百科 (自由的百科全书)