vigilant

1. ADJ Someone who is vigilant gives careful attention to a particular problem or situation and concentrates on noticing any danger or trouble that there might be. 警惕的

He warned the public to be vigilant and report anything suspicious. 他告誡公衆要保持警惕，報告任何可疑情況。

2. vigilanceN-UNCOUNT 警惕

Constant vigilance is needed to combat this evil. 同這種邪惡作鬭爭需要時刻保持警惕。