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.
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Question: Fact: a cavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone

Answer: Kool-aid is a mix of what items as a solution?

Question: Fact: the number of rings in a tree trunk can be used to estimate the age of the tree

Answer: If a tree is being discussed and those talking want to know its age, they will?

Question: Fact: the solar system contains the moon

Answer:
In the 60's people watched on TV while for the first time people walked on?