提防；警戒著；随时准备著
警戒着， 随时准备着， 密切注意着
on the air───在广播，广播中
on the beat───合拍；在巡逻中
on the flat───没有让步条件的
on the slant───倾斜的
on the average───平均而言；一般说来
on the carpet───在考虑中；在审议中
on the market───上市；出售的
in the air───在空中；悬而未决；在流传中；不设防
on alert───警戒状态
She was alwayson the alertfor some new calamities.───她总是保持警觉以防某种新的灾难.
They must be constantlyon the alertfor the enemy.───他们必须随时注意敌人.
Her fears had always beenon the alertfor an upheaval.───她日夜提心吊胆,严防突变.
These are the Chinese need to beon the alert.───这些都是需要中方警惕的.
They were constantlyon the alertnot to be taken by surprise.───他们一直处于常备不懈状态以防突然袭击.
Hearing this, I was instantlyon the alert.───我一听这话, 当下就警惕起来.
The Armies were constantlyon the alertnot to be taken by surprise.───部队一直处于警戒状态以防突然袭击.
An early warning system puts everyoneon the alert.───预警系统让每个成员进入警戒状态.
The policemen wereon the alertfor an excaped convict.───一名逃脱犯令警方全面警戒.
They want to beon the alertfor similar buying opportunities.───他们要准备应对类似的购买机会。
The sentries were allon the alert.───哨兵们都警戒着.
Police are warning the public beon the alertfor suspicious packages.───警方警告公众要警惕可疑包裹.
They did their best to keep on their guard [on the alert] .───他们尽量保持 警惕.
Police are warning the public to beon the alertfor suspicious packages.───警方警告公众要警惕可疑包裹。
Drivers must beon the alertfor traffic signals.───驾驶员必须密切注意交通信号.
Troops areon the alertagainst any possible aggression.───军队戒备着可能的来犯.
Knowing that danger threatened , the sentry wason the alert.───因为知道危险势将发生, 这哨兵加意戒备.
Drivers must beon the alertfor traffic signals.