to indicate that something happened in the past and is now finished.
Often there is a time definition in the sentence, such as: yesterday, last week, two months ago, when I was younger, in 1995.
if you ask a question about something that happened in the past and it starts with the word: when
You make the past simple by putting '-ed' behind the verb.
Examples
I worked
you lived
he, she, it watched
we walked
you talked
they cycled
You make a question sentence with did + infinitive.
You make a negation with didn't + infinitive.
Did I work?
I didn't work.
Did you live?
You didn't live.
Did he watch?
He didn't watch.
Did we walk?
We didn't walk.
Did you talk?
You didn't talk.
Did they cycle?
They didn't cycle.
Spelling
When a verb ends in a consonant + -y, the -y changes to -ie:
I carry - I carried
Note, nothing changes if the verb ends with vowel + -y:
I play - I played
If a verb ends in -e, then only a -d is added in the past simple:
I live - I lived
In the past simple, the last consonant is doubled if it is preceded by one vowel: