Bill Gates has made his mark on the world. So what does he regret?

Not matching a skill that Mark Zuckerberg used last year to impress a Chinese audience: speak a foreign language.

"I feel pretty stupid that I don't know any foreign languages," Gates said Wednesday in an online Reddit chat.

"I took Latin and Greek in high school and got A's and I guess it helps my vocabulary but I wish I knew French or Arabic or Chinese," he said. "I keep hoping to get time to study one of these - probably French because it is the easiest. I did Duolingo for a while but didn't keep it up. Mark Zuckerberg amazingly learned Mandarin and did a Q&A with Chinese students - incredible."

Zuckerberg, founder of Facebook (FB), has become a fairly fluent speaker of Mandarin, a skill he demonstrated during a question-and-answer session with university students in Beijing.

But when Gates visits China -- whether meeting Chinese president Xi Jinping or visiting a Beijing Dairy Queen with Warren Buffett -- he's left to speak in English.

Gates, 59, should have plenty of time to pursue that passion. He's the world's richest man -- worth nearly $80 billion -- and retired from his day-to-day role at Microsoft (MSFT) in 2008. Last year, he shed his role as chairman of the company.

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