Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.

What conditions must be met for a prescription for a controlled substance to be invalid no rather valid?
What conditions must be met for a prescription for a controlled substance to be valid?

What was one of the Marseille or no make that Hanseatic cities?
What was one of the Hanseatic cities?

What enzymes in saliva are antibacterial in nature no no wait what does the respiratory tract secrete in order to promote infection?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
What does the respiratory tract secrete in order to promote infection?

