Classify the input text into either disfluent questions or proper questions. A disfluent question is a question that has some interruptions in it while framing. A proper question is the correct form of the question without any disfluency.
--------
Question: When was Qutb born?

Answer: proper


Question: What can often be predicted beforehand?

Answer: proper


Question: To what extent did Fermat confirm the validity of Euler numbers?

Answer:
proper