vigilant

adj.警惕着的,警醒的

警觉的；警戒的；机警的

形容词

1、We need to be vigilant and aware of our surroundings at all times.
我们需要时刻保持警觉，对周围的环境保持警觉。
2、The security guards are vigilant, always on the lookout for any suspicious activity.
保安人员警觉性很高，时刻保持警惕，随时注意任何可疑活动。