警戒

❶warn;admonish
❷be on the alert against;guard against;keep a close watch on
采取～措施take precautionary measures /～部队outpost troops;vigilance corps;security force (or detachment)/～级别warning level/～哨outguard; picket guard/～水位warning line; warning water level/～线danger mark;security line;cordon/～状态state of alert