alertness
n. 警戒；机敏
例句
Alcohol causes a loss of judgment and alertness.
酒精会使人丧失判断力和警觉性。
The drug improved mental alertness.
这种药物提高了大脑的灵敏度。
《柯林斯英汉双解大词典》
A short nap can promote alertness and improve performance, which are important when you are at work.
小睡一会儿可以提高机警性，提高工作表现，这在你工作时是很重要的。
