Past simple vs Past perfect

We had already eaten when John (come) home.

Last year Juan (pass) all his exams.

When I (get) to the airport I discovered I had forgotten my passport.

I went to the library, then I (buy) some milk and went home.

I opened my handbag to find that I (forget) my credit card.

When we (arrive) at the station, the train had already left.

We got home to find that someone (break) into the house.

I opened the fridge to find that someone (eat) all my chocolate.

I had known my husband for three years when we (get) married.

Julie was very pleased to see that John (clean) the kitchen.