Ответ:

Временные союзы выбираются по смыслу: before — «до того как», when — «когда», then — «затем», after — «после того как».

  1. I have my breakfast before I brush my teeth.
  2. I get up when my alarm clock rings.
  3. On Saturdays we have lunch and then we go shopping.
  4. He watches a film on TV; after he goes to bed.
  5. They always leave out food for the cat before they leave the house.