他回到机场时听到自己的汽车报警器响了。He returned to the airport to find his car alarm going off.是隔壁的报警器。That's next door's alarm.谁拉响了火警报警器？Who set off the fire alarm?...

“报警器”的英语可以翻译为：[计] alertor，announciator，beeper，[化] warner，annunciator ...