Odpowiedź:
1. By the time Mary had woke up her children already went out.
2. Until I travelled to Spain I hadn't never went abroad.
3. When the student had entered the classroom everyone started to write the test.
4. I didn't recognize my friend because he had changed a lot.
5. By the time I had turned forty I become the manager of my company.
6. They couldn't get on the plane because they hadn't buy the tickets.
7. My sister was really hungry because she had forgotten to eat breakfast.
8. When Julie had started the presentation she realized she didn't take her notes.
9. She failed the exam because she hadn't studied at all.
10. There was no food in the fridge because I hadn't done the shopping.
Gdyby coś było nie jasne, to pytaj ;)