Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: Chemical digestion mainly occurs in the small intestine.

Output: Where does chemical digestion mainly occur?


Input: Consider Input: Some compounds form rigid frameworks called crystals.

Output: Some compounds form rigid frameworks called what?


Input: Consider Input: In mammals, air is warmed and humidified in the nasal cavity.
Output: In mammals, air is warmed and humidified in what?