Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Through tubular ducts part do exocrine glands discharge their contents.

Answer: Through what part do exocrine glands discharge their contents?


Question: Saturated hydrocarbons hydrocarbons contain only single bonds between carbon atoms.

Answer: What hydrocarbons contain only single bonds between carbon atoms?


Question: Contour lines show the three-dimensional shape of land.

Answer:
What feature of the land do contour lines show?