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

[Q]: Carbon dioxide is an example of a material that easily undergoes sublimation.
[A]: Carbon dioxide is an example of a material that easily undergoes what?

[Q]: Rainfall weather phenomenon increases the rate of weathering in rock and soil.
[A]: What weather phenomenon increases the rate of weathering in rock and soil?

[Q]: Metallic bonds hold together positive metal ions and their valence electrons.
[A]:
What types of bonds hold together positive metal ions and their valence electrons?