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

[Q]: You call a substance that is not an acid or a base neutral.
[A]: What do you call a substance that is not an acid or a base?


[Q]: When light passes from one medium to another, it changes speed.
[A]: When light passes from one medium to another, it changes what?


[Q]: The understory of the rainforest commonly has ferns and other ground plants.
[A]:
What part of the rainforest commonly has ferns and other ground plants?