PAST PERFECT
FORMS:
Affirmative: HAD + PAST PARTICIPLE (had eaten, had done, had been,...)
Negative: HAD NOT + PAST PARTICIPLE

USE:
· We use this tense to talk about what happened before another event in the past.
· It is used in combination with the past simple. (Revise the Past Simple here: https://www.terceflmc.com/post/past-simple-continuous)
At the airport I realized that I had left my passport at home.
(First, I left my passport at home and then (later) I went to the airport where I noticed I didn’t have it.)
MIND THIS DIFFERENCE!!!
When I got home, my husband left.
(I was at home and then he left.)
When I got home, my husband had left.
(I arrived home after he had left. He had left the house before me.)
ADVERBS
· Already (= before the specified time)
· Still (= as previously)
· Just (= a very short time before the specified time)
· Ever (= at any time before the specified time)
· Never (= at no time before the specified time)
SIGNAL WORDS:
· after
· before
EXPRESSIONS:
· For: I was sorry when the company went bankrupt. I had worked there for twenty years.
· Since: I was sorry when the company went bankrupt. I had worked there since I was 18 years old.
EXAMPLES:
Our holiday wasn’t exactly what we’d expected.
I went to her house, but she’d already left.
Mark had never met anyone so nice before he met Marie.
After we threw the postcard to the post-box, we realized we had forgotten to write the address on it.
EXERCISES
PAST PERFECT (only)
1 https://www.perfect-english-grammar.com/past-perfect-exercise-1.html
2 https://www.grammarbank.com/past-perfect-tense-exercise.html
3 https://www.grammarism.com/past-perfect-exercises/
PAST PERFECT & PAST SIMPLE (combo)
4 https://www.english-grammar.at/online_exercises/tenses/t057-past-past-perfect.htm
5 https://www.perfect-english-grammar.com/past-perfect-exercise-3.html
6 https://www.ego4u.com/en/cram-up/grammar/simpas-pasper/exercises?ex04
7 https://www.ego4u.com/en/cram-up/grammar/simpas-pasper/exercises?ex03
8 https://www.ego4u.com/en/cram-up/grammar/simpas-pasper/exercises?ex06
9 https://www.ego4u.com/en/cram-up/grammar/simpas-pasper/exercises?ex08
TIP!
You should revise irregular verb forms to be able to use correct past participle forms.
Practise them here:
https://www.perfect-english-grammar.com/irregular-verbs-exercise-3.html
https://www.cityu.edu.hk/lc/quiz/irrequiz.htm (all forms)