Which sentence contains an idiom? While Earth has only one moon, planets like Saturn have more than 60. Justin crept by the door
way, quiet as a mouse, because his sister was napping. Margo was over the moon when she hit her first home run in softball. A group of mice is called a mischief, and a group of rhinos is called a crash.
The sentence that contains an idiom is "Margo was over the moon when she hit her first homerun in softball."
Explanation:
The first and last sentences are facts, and the second sentence contains a metaphor, but not an idiom. The third sentence is the sentence that contains an idiom because an idiom is a phrase that is well known but does not have a literal meaning, and "over the moon" is a well-known phrase with no literal meaning.