The whole navy was placed on full alert.

整个海都处于全面戒备状态。

Warnings of an enemy attack forced the troops onto the defensive.

敌出进攻的迹象，部队不得不进入戒备状态。

The patrol police on duty are on the alert against any possible disturbances.

"值班巡警处于戒备状态,随准备应付任何可能发生的骚乱。"

The dog jealously guarded its bone.

那狗戒备地看管着它的骨头。