keep a watch out for somebody/something (also be on the watch for somebody/something)LOOK FOR to be looking and waiting for something that might happen or someone you might see, especially so that you can avoid danger, trouble etc 小心提防某人/某事物,对某人/某事物保持戒备 Be on the watch for anything suspicious. 注意任何可疑情况。
→ keep a watch out for somebody/something at watch2(1)