2. While I looked for my keys, I remembered I left them at home.
...While I was looking for my keys, I remembered I had left them at home...

3. Paula had used to play tennis when she had been at school.
...Paula used to play tennis when she was at school...

4. When I got into bed, I was falling asleep immediately.
...When I got into bed, I fell asleep immediately...

5. When I was finally finding the house, I was knocking at the door.
...When I finally found the house, I knocked at the door...

6. After Jill was giving Nick his books, she went home.
...After Jill gave Nick his books, she went home...

7. Maria would live in Sweden when she was a child.
...Maria used to live in Sweden when she was a child...

8. I was using to get up early when I had gone sailing.
...I used to get up early when I went sailing...

9. The Vikings had sailed to North America a thousand years ago.
...The Vikings sailed to North America a thousand years ago...

10. Juliet was sure she was seeing the tall man before.
...Juliet was sure she had seen the tall man before...