1. By the time Mary woke up her children had already gone out.
2. Until I travelled to Spain I had never gone abroad.
3. When the student entered the classroom everyone had started to write the test.
4. I didn't recognize my friend because he had changed a lot.
5. By the time I turned forty I had become the manager of my company.
6. They couldn't get on the plane because they hadn't bought the tickets.
7. My sister was really hungry because she had forgotten to eat breakfast.
8. When Julie started the presentation she realized she hadn't taken 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.