Simple Past x Past Continuous: Quando usar

Quando devo utilizar o Simple past e o Past continuous?

Estou tentando fazer o seguinte exercício:

A. James...(meet) her when she...(sing) in a rock show.
B. ...you...(burn) your hand while you...(cook)?
C. Carol...(cry) while she...(watch) a film.
D. It...(rain) when I...(leave)the office so I...(take) my umbrella.
E. When we...(arrive) at the station, the train...(leave).

Thank you in advance!