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: metal is a nonrenewable resource
Unlike trees in the forest or a pond full of fish, metal is only available until?

Fact: plants are a source of oxygen through photosynthesis
Chloroplasts in shrubs scrub carbon from the air and return?

Fact: if the atmospheric temperature rises then the glaciers will melt

Glacier melt?