alert
[ə'lə:t]
adj.警觉的, 灵敏的
vt.使意识到, 警惕
n.警戒, 警报
例句与用法：
Troops are on the alert against any possible aggression.
军队戒备着可能的来犯。
The alert leopard went up to a deer quietly.
警觉的豹子静悄悄地走近一只鹿。
Although he's over eighty his mind is still remarkably alert.
他虽已年过八十，但头脑仍然十分机敏。
An alert listener will have noticed the error.
耳朵尖的人能听出这个错。
词形变化：
动词过去式: alerted | 动词过去分词: alerted | 动词现在分词: alerting | 动词第三人称单数: alerts |
详细释义：
a.
1. 警觉的; 警惕的; 留神的[(+to)]
She is alert to every sound and movement.
她对每一个声音和动作都很警觉。
2. 机敏的, 灵活的[(+in)]
The boy was alert in answering the stranger's questions.
男孩很机敏地回答了陌生人的问题。
n.[C]
1. 警戒, 警报
2. 警戒状态; 警戒期间
She was always on the alert for some new calamities.
她总是保持警觉以防某种新的灾难。
vt.
1. 向……报警; 使警觉; 使注意[(+to)]
The doctor alerted me to the danger of a heart attack.
医生提醒我注意心脏病发作的危险。
2. 通知(军队, 船只等)待命; 通知[(+for/about)][O2]
She's alerted me for weekend duty.
她已通知我周末值班。
短语词组：
on the alert
1. 警戒着; 随时准备着
They have put the army on the alert.
他们已使军队进入戒备状态。