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.

Input: Consider Input: Fact: boiling means change from a liquid into a gas by adding heat energy.

Output: boiling change.

Input: Consider Input: Fact: completing a circuit causes electricity to flow through that circuit.

Output: circuit completed.

Input: Consider Input: Fact: a sifter is used for separating mixtures.
Output: Sifter.