You use the past participle, often known as past participle.

• Subject + had /hadn't + past participle, second event.
• I had walked home by the time he arrived.
• I hadn't walked home by the time he arrived.
• Second event + subject + had / hadn't + past participle.
• By the time he arrived, I had walked home.
• By the time he arrived, I hadn't walked home.

Contractions

• I had I'd
• I had walked home by the time it was dark. I'd walked home by the time it was dark.
• I had not I hadn't
• I had not walked home by the time he arrived. I hadn't walked home by the time he arrived.

Using the Past Perfect to Tell a Story About the Past.

• I'd never been abroad before, but then I moved to Australia.
• The boat had sailed by the time he reached the docks.
• They had met a long time ago.

Using the past perfect to describe something that happened.

• The rain still hadn't stopped by the time we reached the top of the mountain.
• It had been a long, hot summer.
• He'd walked all day.

Using the Past Perfect to Talk about Past Events but not in the Order They Happened.

• By the time I reached the shop, I had walked a long way.
• I called his office, but he had already left.
• It was June, but it still hadn't rained.

Using the Past Perfect to Report an Event.

• I had stood for about five minutes when the robber came in.
• I'd decided to tell the truth before I came here.
• She'd started working at 8 when she was the first one there.

Use the Past Perfect to Report on Things Said.

• My teacher had told me to draw, but I couldn't find my pencil.
• He told me he'd gone shopping.
• I said I hadn't reported it yet.

Use the Past Perfect to Express Regret.

• I wish I'd tried harder at school.
• I wish I'd lived a healthier life.
• I wish I had spent more time with my parents.

Use the Past Perfect for the Third Conditional.

• If my alarm had gone off, I wouldn't have been late to work.
• If there hadn't been so much traffic, we wouldn't have missed our flight.
• If he'd studied harder, he would have passed the exam.

• Before

• Any time before the past perfect event.
• She'd never been there before.
• The policeman had arrested the thief before you got here.
• They'd met before
.

• Already

• Before, but not long before, the past perfect event.
• The boat had already sailed by the time he got to the docks.
• I had already finished before that moment.
• By then, we'd already completed the project.

• Still

• Before and right up to the past perfect event.
• It still hadn't rained by June.
• By the time I left, it still hadn't arrived.
• Back then, I had still dreamed of being a ballerina.

• Just

• A very short time before the past perfect event.
• I had just arrived before it started to rain.
• It was nighttime, and they'd just fallen asleep.
• He had hoped she would come.

• Ever

• All the time before the past perfect event.
• It was the most beautiful sight I had ever seen.
• Hadn't he ever visited Norway before?
• Had our company ever tried to work differently, they be doing better now.

• Never

• At no time before the past perfect event.
• I had never been abroad until I moved to Australia.
• Before that night, I had never walked home alone.
• She had never been there.

• By the time

• Right up to the secondary event
• By the time I'd got there, she'd gone.
• I had forgotten what I wanted by the time I got to the shop.
• By the time they had finished, everyone was bored.

• When

• Near the same time but before the secondary event.
• When is often combined with just.
• The thief had just escaped when the police arrived.
• I'd just gone inside when it started to rain.
• We'd just eaten when they told us to leave.