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

What were Kublai Khan's successors no the Yuan armies too weak to stop?
What were the Yuan armies too weak to stop?

What rather who identified gravity as a force?
Who identified gravity as a force?

What benefits, sorry, area of science is understanding slowly changing?
What area of science is understanding slowly changing?