instruction:
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.
question:
Fact: Matter in the gas phase has variable shape
answer:
A solid has a fixed shape. When liquid is boiled and turns into gas, its shape is?

question:
Fact: grey clouds are a source of precipitation
answer:
A sky that is mostly this color will likely be precipitating:?

question:
Fact: food is a source of energy for animals
answer:
What is a source of energy for animals?