Setting Off The Alarm的意思|示意

What puzzles me is how the burglar got into the house without setting off the alarm.

令我迷惑的是抢匪是如何在不引发报警器的情况下进入屋子的。

I did not hear any jet aircraft in the area which I thought was weird because I was just outside of Andrews air Force base and you can't get near that place without setting off some sort of alarm.

我没有听到任何在该地区，我觉得真是奇怪，因为我是刚刚安德鲁斯空军基地外，你无法靠近那个地方得到了一些没有设置报警排序喷气飞机。