Narrative tenses: past simple and past continuous

Background and interruption

The past continuous (was/were + -ing) sets the scene — a longer action already in progress. The past simple is the shorter action that cuts across it: I was walking home when it started to rain.

Notice the pattern: while or as usually goes with the continuous, and when usually goes with the simple.

Two things at once

Both continuous: While she was cooking, her brother was doing his homework.

What continuous cannot do

Some verbs describe states, not actions — know, believe, want, belong, understand. They are not used in the continuous, so I was knowing the answer is wrong.