sentence: It took longer to study for the history test than it did for the math exam. That's because the teacher is tougher in
complete: history .

sentence: Tanya had a bad case of diarrhea but Katrina did not.
complete: Katrina didn't soil the pants they were wearing.

sentence: The windows were very dirty, but Joseph saw no reason to clean them while William immediately cleaned them.
complete:
Joseph was a naturally dirty person.