What does Mais qui mean in English?

"Mais qui" in French means "But who" or "Who, though?" It's a phrase that expresses surprise or disbelief, often used in a rhetorical way.

Here are some examples:

* "Mais qui a fait ça?" (But who did this?) - You're surprised or shocked by something that happened.

* "Mais qui est-ce?" (Who is this?) - You don't recognize someone or are surprised by their appearance.

* "Mais qui vous a dit ça?" (Who told you that?) - You're questioning the source of information or are surprised by what you've heard.

The emphasis is on the "qui" (who), implying a questioning and often skeptical tone.