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

Q: What is er uh what evolved in later vertebrates?

A: What evolved in later vertebrates?
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Q: How did or no rather what did Mongols worship?

A: What did Mongols worship?
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Q: Why was DS-3 er instead the OC-12c considered a substantial engineering feat?

A:
Why was OC-12c considered a substantial engineering feat? 
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