Выручите пожалуйста))* The past continuous indicates on ongoing activity while simple

Выручите пожалуйста))*
The past continuous indicates on ongoing activity while simple past indicates a finished action. Look and circle the correct form of the verb.
1. I was reading/ read a book when my mother was coming/ came in.
2. He was taking/ took a shower when the lights went/ were going off.
3. The rain started/ was starting to fall while we walked/ were walking in the park.
4. We were eating/ ate our dinner when someone knocked/ was knosking an the door.
5. The were walking/ walkid to school when suddenly they saw/ were seeing an unusual lught.