1. Everyone (enjoyed/was enjoying)himself at the party.
2. we reached the lake Just as the sun (set/was setting).
3. the family (was/were)eating dinner when the telephone rang.
4. the hero was embracing the heroine when someone in theater shouted FIRE.(meaning)
People are looking a film or a play about a hero and a heroine and someone of the audience shouts FIRE.
I think so