Ответ:

Corrected sentences:

  1. Philip was washing the car while the fire was starting.
  2. Neil was studying when his sister was listening to music.
  3. Harriet opened the door and walked into the house.
  4. We were having lunch at a lovely restaurant every day when we were on holiday.
  5. Brian was drinking tea at five o'clock yesterday afternoon.
  6. Dad was repairing the TV while Mum was cooking dinner.
  7. I went to the cinema last Saturday.
  8. I was buying a new dress for my party yesterday.
  9. While Jeff was building the garden shed, he hurt himself.
  10. While the teacher was speaking, the students were listening to him.