Respuesta:
Explicación:
The students were doing an exercise when the bell rang
I saw an accident while i was waiting at the bus stop.
When my mom came home, my sister was sleeping
We found some old photographs while we were tidying our room
When you called me last night, I was studying for the test
I had a bad dream while i was sleeping on the sofa
When the fire alarm went off, we were listening to music
She started to cry while she was watching a movie
