text: Rita: got a minute?
  Susan: Yep, what’s up?
  Rita: need  help. Got test in English grammar tomorrow.
  Susan: shoot.
  Rita: what’s the main difference b’tween past simple and past continuous?
  Susan: oh, c’mon, it’s trite.
  Rita: oh yeah, smart ass? So?
  Susan: Simple past describes complete past action and past continuous describes incomplete past action.
  Rita: That’s it?
  Susan: Yes, basically. Get the grammar book for the rest Good luck. 
target: Rita is having test in English grammar tomorrow.