Negative:

I didn't swim yesterday.

Nor did I.

Question:

Did you swim yesterday?

Positive:

I swam yesterday.

https://www.englishclub.com/grammar/verb-tenses_past_quiz.htm

I was reading when the phone rang.

I was sleeping when the postman rang.

I was shopping when I lost my bag.

I was drying my hair when the blackout started.

I was feeding the dogs when the neighbour's cat jumped up the fence.