1) A: what caused the accident?
B: the driver losed control of the car and then it crashed in another vehicle.
2) A: are you heard the thunder?
B: yes, i was walking back home at the time.
3) A: while the plane was landing, an engine cought fire.
B: that's terrible are everyone got out alive?
4) A: what were you doing when the earthquake started?
B: i was reading a magazine while Laura was cooking.