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

At which or no rather what time did a river system develop in the Upper Rhine Graben?
What time did a river system develop in the Upper Rhine Graben?

What is the tentacle ermm rather mouth of a pleuobrachia kept in?
What is the mouth of a pleuobrachia kept in?

Where did no uh i meant where was Halford Mackinder born?
Where was Halford Mackinder born?