The past participle (the third form: go → gone) never stands alone. It builds the perfect tenses with have/has/had (I have seen it) and the passive voice with be (The house was built in 1990). For regular verbs it looks exactly like the past simple (-ed); for irregular verbs it is the third column of the classic table: go → went → gone, see → saw → seen, take → took → taken.
When to use it
Present Perfect: experience / result I have never eaten sushi. — I have never eaten sushi.
Past Perfect: earlier past The train had left when we arrived. — The train had left when we arrived.
Passive voice This book was written in 1950. — This book was written in 1950.
Endings · Conjugation
+ -ed
-ed
worked
-e → -d
-d
lived
consonant + y → -ied
-ied
studied
doubling
-ped
stopped
Irregular verbs
go
gone
see
seen
write
written
Don't just read this, drill it
Verboteca drills every verb form with spaced repetition until it becomes automatic.