Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.
Example: Who did the Han Chinese want to help the Khitan no I mean the Mongols fight?
Example solution: Who did the Han Chinese want to help the Mongols fight?
Example explanation: The input initially means Khitan and then changes to Mongols, hence this is correct.

Problem: What is the chemical, no what is a mechanical barrier in insects that protects the insect?
Solution: What is a mechanical barrier in insects that protects the insect?