1. 警觉的;警惕的;留神的;机敏的
If you are alert, you are paying full attention to things around you and are able to deal with anything that might happen.
e.g. We all have to stay alert...
我们大家都必须保持警惕。
e.g. He had been spotted by an alert neighbour.
一个警觉的邻居发现了他。
形容词警觉的,警惕的,注意的; 思维敏捷的; 活泼的
名词警报; 警戒状态
及物动词向…报警