alert

名词 alert:

1. condition of heightened watchfulness or preparation for action
   同义词：qui vive
2. a warning serves to make you more alert to danger
   同义词：alerting
3. an automatic signal (usually a sound) warning of danger
   同义词：alarm, warning signal, alarum

动词 alert:

1. warn or arouse to a sense of danger or call to a state of preparedness
   同义词：alarm

形容词 alert:

1. very attentive or observant
2. mentally responsive
3. not unconscious; especially having become conscious
   同义词：awake
4. (usually followed by `to') showing acute awareness; mentally perceptive
   同义词：alive, awake

1. Troops are on the alert against any possible aggression.
   军队戒备着可能的来犯。
2. The alert leopard went up to a deer quietly.
   警觉的豹子静悄悄地走近一只鹿。
3. 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。
4. An alert listener will have noticed the error.
   耳朵尖的人能听出这个错。