<p>I can only speak for myself. I’m of Chinese descent so prior to college, I had about 8 years of Saturday morning Chinese school. I ended up taking Intensive Chinese I during my freshman year in college to satisfy the foreign language requirement because it was easier for me than continuing high school French. There was one student who just did not do very well in that class - he would move his head in the direction of the tones.</p>
<p>Fastforward four years. I’m at the Peace Hotel in Shanghai and I heard this very distinctive voice speaking Chinese fluently. It was that not very good student from freshman year! So, I would say any student, through hard work, can become very fluent (he also could read and write) from four years in college.</p>