PAST PERFECT

past participle

100

ring 

rung

200

go

gone

300

lose

lost

400

bring 

brought

make past perfect

100

John went to work.

Then Mary rang John's doorbell.

Mary rang John's doorbell but John had gone to work.

200

I lost his number.

Then I was pleased when I got a text from Jim.

I was pleased when I got a text from Jim because I had lost his number.

300

I forgot to set the alarm.

then I woke up late.

I woke up late, because I had forgotten to set the alarm.

400

They left the tickets at home.

They got to the station.

When ...., they realized 

When they got to the station, they realized they had left the tickets at home.

what happened first

100

I hadn't bought a towel, so I couldn't have a shower.

I had not bought a towel

200

The plane had left by the time I got to the airport.

The plane had left

300

They passed the exam because they had practiced a lot. 

They had practiced a lot.

400

You had studied Italian before you moved to Rome.

You had studied Italian