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

Example input: Who did the Han Chinese want to help the Khitan no I mean the Mongols fight?
Example output: 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.
Q: Which are the or no make that what are the phagocytes that are located in tissues in contact with the external environment called?
A:
What are the phagocytes that are located in tissues in contact with the external environment called?