How to Fix Incorrect Word Usage in a Sentence

Explanation:

In the sentence, "Their" is used incorrectly. The word "Their" is a possessive pronoun, indicating ownership or belonging. In this case, it is incorrectly suggesting that Mario and Olivia own the action of starring in the commercial.

The correct word that should be used is "They're," which is a contraction of "They are." By using "They're," the sentence would read: "Mario and Olivia are champion snowboarders. They're starring in an upcoming commercial for a national sporting goods store."

It is important to be mindful of the correct usage of words in sentences to ensure clarity and accuracy in communication. By replacing "Their" with "They're," the sentence becomes grammatically correct and conveys the intended meaning more effectively.