Past Continuous or Past Simple?

They ...................... (talk) when the lesson ...................... (start).

Katie ...................... (not listen) when the teacher ...................... (ask) her a question.

She ...................... (not go) to the party.

We ...................... (study) when the teacher ...................... (arrive).

I ...................... (sleep) when you ...................... (ring).

He ...................... (feel) cold when he ...................... (wear)

It ...................... (snow) when we ...................... (leave) home.

As I ...................... (watch) TV, the door bell ...................... (ring).

The dog ...................... (run) after the cat when it ...................... (fall).

Adonis ...................... (look) through the window when he ...................... (see) a huge bird.