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: What did Niels Jerne formulate before the 1950s no Frank Burnet?

Answer: disfluent


Question: Why were Northern Chinese ranked higher?

Answer: proper


Question: What book did Darwin publish in 1830?

Answer:
proper