When the teacher ... (ARRIVE) the students were sitting.
When I got up this morning, the sun ... (SHINE)
While the children were playing in the park, Sarah ... (READ) a book.
When Tom was walking on the beach, he ... (FIND) a treasure.
When David was rollerblading, he ... (FALL).
When Brian ... (DRIVE) his car, he hit a tree.
Carla and Fred ... (TALK) when the accident happened.
When Sally ... (SEE) the accident, she called an ambulance immediately.
While the teacher was talking, Tom ... (SLEEP).
While the teacher was talking, the students ... (LISTEN).