I was doing (past continuous) and
I did (past simple)
I have done (present perfect) and
I did (past simple)
Anant was reading a book. The phone rang. He stopped reading.
He answered the phone.
What happened? The phone rang, (past simple)
What was Jack doing when the phone rang? }
He was reading a book. } (Past continuous)
What did he do when the phone rang? }
He stopped reading and answered the phone,} (past simple)
Jack began reading before the phone rang.
So: When the phone rang, he was reading.
Past simple
Examples:
A: What did you do yesterday morning?
B: We played tennis, (from 10 to 11.30)
Jaya read a book yesterday. (= from beginning to end)
Did you watch the film on television last night?
It didn't rain while we were on holiday.
Past continuous
Examples
A: What were you doing at 10.30?
B: We were playing tennis.
Jaya was reading a book when the phone rang.
Were you watching television when I phoned you?
It wasn't raining when I got up.
I started work at 9 o'clock and finished at 4.30. At 2.30 I was working.
It was raining when we went out. (= it started raining before we went out)
I saw Ravi and Kavi this morning. They were waiting at the bus stop.
Aysha fell asleep while she was reading.