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

Example Input: Compounds with metals and nonmetals sharing electrons are known as ions kinds of compounds.
Example Output: Compounds with metals and nonmetals sharing electrons are known as what kinds of compounds?

Example Input: An acorn growing into an adult tree will take the longest time to observe.
Example Output: Which of these will take the LONGEST time to observe?

Example Input: Compounds containing an atom of nitrogen element, bonded in a hydrocarbon framework, are classified as amines.
Example Output:
Compounds containing an atom of what element, bonded in a hydrocarbon framework, are classified as amines?