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.

Input: Consider Input: Fact: grey clouds appear before precipitation

Output: In the intermediary before rain falls, observers may note?

Input: Consider Input: Fact: as air pressure decreases , the chance of rain will increase

Output: The pressure in air drops very low, so clouds?

Input: Consider Input: Fact: humans cause pollution
Output: What is more likely to have caused pollution in the air?