Answer:
It is in verb tense. She was laughing at every joke her brother told.
She is your subject.
What is she doing? Laughing. That's your verb
Laughing at/to whom or what?
Joke. That is your direct object.
Who had/told the joke? her brother. He is predicate nominative.
Just because it doesn't end with "LY" doesn't mean it's not a verb.
Very glad I could help!
