In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Q: Fact: optical tools are used for observing materials up close.

A: materials.
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Q: Fact: freezing causes a solid to form.

A: freeze molecules.
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Q: Fact: Milk is a nutritious fluid.

A:
milk comes.
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