Past Perfect

How to build it

• Affirmative: had + past participle: She had written the letter. The same for all persons; short form I’d, she’d, they’d.
• Negative: hadn’t + past participle: She hadn’t written the letter.
• Question: Had + subject + past participle: Had she written the letter before he arrived?
• she’d can be she had or she would: she’d gone (had), she’d go (would).

When to use it

• An action that happened before another past action or moment — “the past before the past”: When I got to the station, the train had left.
• Explaining a past situation by something earlier: She was upset because she’d lost her phone.
• Reported speech, when the original sentence was in the Past Simple or Present Perfect: He said he had seen the film.
• Unreal past conditions (third conditional) and wishes: If I had known, I would have helped. I wish I had studied harder.
• With by the time, already, before, after, just, never… before: By the time we arrived, they had already eaten.

Examples

• I had never flown before that trip.
• When we came back, someone had broken into the flat.
• She told me she’d finished the project.
• They had already left when I called.
• Had you met him before the wedding?

Common mistakes

• Using it for any “old” past: I had visited Lviv in 2010 → I visited Lviv in 2010. It’s only needed when you compare with a later past moment.
• Overusing it with before/after: when before or after already shows the order, the Past Simple is fine: After she left, I went to bed.
• Forgetting it in sequences that go back in time: When I arrived, the film started means it started as I arrived; the film had started means I missed the beginning.
• Tense shift in reported speech: She said she has lost her keys → She said she had lost her keys (when the situation is no longer current).

The passive

had + been + V3: The letter had been written. Common in stories and reports: When the police arrived, the money had already been taken. The house had been sold before we could make an offer.