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.

Example Input: Fact: Birds move their wings using muscles in the chest.
Example Output: Birds move their wings using muscles in the chest.

Example Input: Fact: unequal heating of Earth 's surface by the Sun causes global wind patterns.
Example Output: earth our planet.

Example Input: Fact: Some species of reptiles can go several weeks between meals.
Example Output:
meal is a food.