BEIJING — China may ban Facebook, but not its co-founder and CEO Mark Zuckerberg, who spoke to students in Beijing in a 30-minute chat Wednesday in his recently learned Mandarin Chinese.

There was no explicit discussion of China’s ban on the social media site, which has been in place since 2009.

Zuckerberg noted Facebook already helps some Chinese companies in foreign markets, citing computer maker Lenovo’s ads on Facebook in India.