1. yesterday I ... (went shopping)
2. while I ... (was walking) home I suddenly ... (felt) an awful pain in my back.
3. He ... (has gone) to the doctor three times already this week.
4. Julia ... (has been) ill since she ... (came) back from England last week.
5. When I ... (arrived) Christine.... как будто предложение не дописано, смысл непонятен