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

Example Input: Glycerol is a triol, an alcohol which contains three hydroxl functional groups.
Example Output: Glycerol is a triol, an alcohol which contains three what?

Example Input: Rubber is an example of a(n) insulators that does not allow electrons to move through them.
Example Output: Rubber is an example of what type of substances that do not allow electrons to move through them?

Example Input: Exchange of dna segments happens between non-sister chromatids of homologous chromosomes during crossing-over.
Example Output:
When does exchange of dna segments happen between non-sister chromatids of homologous chromosomes?