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. 他告诫公众要保持警惕，报告任何可疑情况。

2. vigilanceN-UNCOUNT 警惕

Constant vigilance is needed to combat this evil. 同这种邪恶作斗争需要时刻保持警惕。