Past Participle
buy
bought
I/have/see/him/before. (NEGATIVE)
I have never seen him before.
I haven't seen him before.
have
had
We/arrive/at 8:05, but the train/already/leave. (AFFIRMATIVE)
We arrived at 8:05, but the train had already left.
go
gone
get
gotten
Our mum/find/the keys.
Our mum hasn't found the keys.
I heard students laughing, and then I heard a loud noise. What/they/do? (QUESTION)
I heard students laughing, and then I heard a loud noise. WHAT HAD THEY DONE?
By the time my father/call/I/leave/the party. (AFFIRMATIVE)
By the time my father called, I had left the party.