讲解：
go off
(警报器等)突然发出巨响
The alram is going off due to the fire.
起火了，警报器发出巨响。

omen (for sth)
预兆；前兆；征兆
a good / bad omen 吉祥的/不祥的预兆
The omens for their future success are not good.
他们未来成功的预兆不祥。

raise the alarm
提高警觉
I hammered on all the doors to raise the alarm.
我敲打所有的门让大家警觉。

escort sb
护卫；护送:
The President arrived, escorted by twelve soldiers.
总统在十二名衞兵的护送下到达。

apologize (to sb) (for sth)
道歉；谢罪:
Why should I apologize?
我为什么要道歉？