n. condition of heightened watchfulness or preparation for action
n. a warning serves to make you more alert to danger
a. engaged in or accustomed to close observation
s. quick and energetic
a. 警觉的, 灵敏的, 留心的
n. 警报
vt. 使警觉, 通知, 使意识到
1. The teacher asked the students to stay alert during the lesson.
老师要求学生在课堂上保持警觉。
2. You should be alert for any signs of danger while hiking.
你在远足时应该注意任何危险的迹象。
3. The alert on my phone warned me about the severe weather.
我手机上的警报提醒我天气恶劣。