Student or Learner
orignal sentence: If the scientists hadn't been so careful, they might never have discovered a cure for the disease.
changed sentence: A cure to the disease might never have been discovered had not the scientists so careful.
Question: Why should the preposition 'for' in the orignal sentence be 'to', when it was changed to the second sentence? Thanks a lot, in advance.
I would use 'for' in both sentences.