story: The students heard the fire alarm. They were worried, but their teacher calmly lined them up at the door. They were led into a field. The students learned that the fire alarms was just a drill exercise. The students were relieved as they returned to class.
 selected sentence: They were worried, but their teacher calmly lined them up at the door.
The students hear the fire alarm >Causes/Enables> They line up at the door