Given a fact, create a question that can be answered using the fact. Construct the question such that it is unambiguous, has a unique answer and the answer can be given using the fact.

Fact: large trees block sunlight from reaching the ground
Large trees block sunlight from reaching what?

Fact: when a plant grows , the number of the leaves of that plant may increase
as an evergreen matures and grows, it's leaves tend to?

Fact: fire causes harm to living things

If a thing experiences a burning combustion, then it is?