I am chinese, but was born in the states and English is my primary language. When I was little, my parents spoke cantonese a lot so now I can speak it very well. I can understand a little bit of mandarin, but I can't write chinese at all. Can I take chinese as a course in college? In other words, would it be okay for me to take chinese even though I understand it a little? Would it be weird?

I know how to read a handful of Chinese words, but don't know how to speak in Chinese at all. Then today I tried to look a little bit into pronuciation and I got stuck pretty quickly because I couldn't hear the difference between 机上面 and 机下面. It seems kind of important too, being that they are oppisites of each other.