Ответ:

1. By the time Olivia had arrived home, it started raining.

2. Luckily, Sam had already left the house when the earthquake hit.

3. We saw all the damage to the house after the sto had finished.

4. I had got out of the collapsed building before the rescue team arrived.

Объяснение:

То действие, которое случилось до какого-то события (например, до другого действия), должно быть в past perfect.