alert
英 [əˈlɜːt]   美 [əˈlɜːrt]  
adj.
警觉的;警惕的;戒备的;意识到;注意到
vt.
向…报警;使警觉;使警惕;使戒备;使意识到;使认识到
n.
警戒;戒备;警惕;警报

例句

Suddenly he found himself awake and fully alert.

突然他发觉自己醒了过来，而且高度警觉。

Alerted by a noise downstairs, he sat up and turned on the light.

楼下的响声使他警觉，他坐起来打开灯。

They had been alerted to the possibility of further price rises.

他们已意识到价格可能继续上涨。