must be "Can you speak Chinese?" = 你 会 说 汉语 吗？

你知道中国人

你会说中文吗

你懂中文吗?[nǐ] [dǒng] [zhōng] [wén] [ma}? 你会中文吗?[nǐ] [huì] [zhōng] [wén] [ma]?

I think the most common way to say it is: 你会中文吗？