報警

In a sentence

• 如果发现火灾，请立即報警。

  If you discover a fire, please immediately report it to the police.

  Here, '報警' (to report to the police) is used in the context of alerting authorities about an emergency situation, specifically a fire incident.

• 小偷企图进入住宅，住户赶紧報警。

  A thief attempted to enter the residence, so the occupant quickly called the police.

  In this sentence, '報警' is employed to describe the action of contacting law enforcement when a criminal activity is observed, in this case a burglary attempt.

• 听到奇怪的声音，邻居以为发生犯罪而報警。

  Upon hearing strange sounds, the neighbor suspected a crime and called the police.

  Here, '報警' indicates reporting to the police due to suspicion of wrongful acts, exemplifying its use in uncertain but potentially dangerous situations.