What (you/do) ... when the phone (ring) ...?
were you doing / rang
She (write) ... an email while her sister (watch) ... TV.
was writing / was watching
I (hear) ... a loud noise while I (sleep) ... last night.
heard / was sleeping
We (have) ... dinner when the lights (go) ... out.
were having / went
They (play) ... soccer when it suddenly (start) ... to rain.
were playing / started
I (read) a book while my mom (cook) in the kitchen.
Was reading/ was cooking
They (talk) ... to each other when the teacher (enter) ... the classroom.
were talking / entered
While I (walk) ... to school, I (see) ... a strange animal.
was walking / saw