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: using tools is a learned characteristic
a learned characteristic is a?

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

Fact: acid rain has a negative impact on water quality

If it starts raining acid rain you should?