Past Perfect, Past Perfect Continuous or Past Simple?

1. I ……………………..(work) for the company for three months before I ……………….(realize) my neighbour also worked there.
2. As soon as George …………………..(finish) the race, he …………………(drink) 3 glasses of water.
3. Everything …………………(be) white because it ……………………(snow) all night.
4. My parents …………….(be) really happy when I …………………(qualify) because they ……………………..(always want) me to be a doctor.
5. She ………………..(be) exhausted when she …………………..(get out) of the pool because she ……………………… (swim) 3 kilometers.
6. We ……………………….(only sit) down when the waitress ………………….(come) to take our order.
7. I could tell from their faces that they ……………………….(argue) about something.
8. Our dinner ………………… (not be) ready because I ………………..(forget) to switch the oven on.
9. By the time the doctor …………………(arrive), the baby …………………..(be born).
10. After John ………………….(finish) his dinner he………………….. (go) straight to bed.