alarm, alert

做动词时:
alarm - make sb feel worried or frightened

alert
1. make sb aware of sth
2. warn sb to watch for danger and be ready to act

做名词时的例句:
1. Ross set off the fire alarm by accident.
2. The alarm's going off. [ringing]
3. Voice from Outside: Phoebe Buffay! Phoebe: Fire Alarm? [Phoebe家的fire alarm坏了，响个不停。她用有自己名字的毯子把它裹起来扔掉了，有人又给捡回来了敲门，她以为Fire Alarm自己找回来了]
4. When you think something dangerous is about to happen, but then discover that you were mistaken, you can say that it was a false alarm.
5. An alarm clock (or alarm) is a clock that you can set to make a noise so that it wakes you up at a particular time.
6. A car alarm is a device in a car which makes a loud noise if anyone tries to break into the vehicle.
7. Neighbours raised the alarm when they smelled smoke.
8. If alarm bells ring, you feel worried that something bad may be happening.
9. The bunny raised its head, suddenly alert.
10. The French should have been alert to the possibility of invasion.
11. The bank is alert to the danger.
12. The crew immediately alerted the Downing Street. [有本小说说有潜艇船员发现了去珍珠港的日本舰队并alert了唐宁街(英国政府)]
13. A red alert is a warning that there is very great danger.
14. If a hospital, a police force, or a military force is on red alert, they have been warned that there may be an emergency.