I don't understand you. 和 I don't your understand哪个对?为什么?

I don't understand you. 和 I don't your understand哪个对?为什么?
I don't understand you.
和
I don't your understand
哪个对?为什么?

I don't understand you. 和 I don't your understand哪个对?为什么?
第一句I don't understand you.是对的,意为:我不明白(听不懂)你在说什么.
第二句助动词否定式don't 后面要跟动词原形作谓语,此句缺少作谓语的动词,本身不成句子.语法错误.

当然是I don't understand you. 对.意思:是我不明白你的意思

I don't understand you
因为我们可以用中国式翻译法:
i-我
don't－－不
understand－－－理解
you --你
而I don't your understand用此法则翻译出的汉语是说不通的