5. 12 Why didn't the alarm clock go off?

5. 12 Why is there no sound when calling the police? The reason for this is the following：

1. Alarm is damaged: there may be bad weather the day before or the day before, and wind and rain may damage the alarm, resulting in no sound.

2. Maintenance is not timely: road construction or other reasons may lead to alarm failure, and maintenance personnel's untimely maintenance may lead to alarm failure.

3. System failure: Because the disaster prevention and early warning system has a complicated relationship with other systems such as power system, system failure in one place may affect the whole system operation in all other places.