Explain the difference in emphasis or nuance between saying "Can you repeat that again?" and "Can you repeat that?"

The difference in emphasis between "Can you repeat that again?" and "Can you repeat that?" lies in the redundancy of "again."

• "Can you repeat that?" is the standard and grammatically correct way to ask someone to say something one more time. It implies you didn't hear or understand it the first time.
• "Can you repeat that again?" is redundant because "repeat" already means to "say or do again." While commonly used in informal speech, it can sometimes imply frustration or a lack of attention if used in a specific tone, as it literally asks for something to be repeated for a second time after it has already been repeated once.

The phrase "Can you repeat that?" is more concise and generally preferred.