警惕性的英文：
alertness

An alert pharmacist will save a doctor from his own mistake by querying a prescription.
警惕性很高的药剂师对处方提出疑问而避免了医生的错误。

You cannot afford to relax your vigilance for a moment.
警惕性是一刻也不可放松的。

be awake, be alert, be there.
处于醒着的状态，且警惕性很高。

Suddenly the combat alert sounded.
突然战斗警报响了。

conflict alert (CA)
碰撞警告

She was very brisk and alert.
她完全是一副干脆利落、精神抖擞的神情。

They have put the army on the alert.
他们已使军队进入戒备状态。

Don't alert the enemy.
不要惊动敌人。