sfuqua wrote:Once again, I'm sorry about using the "F" word.
You made my day!
But jokes aside, a student at the university is an adult so she on he can definitely learn two languages at the same time. They have plenty of free time. Will they reach C1 in both of them? Well, if it's something like English and German for a speaker of Slavic languages, I guess it might be doable. But if it's Arabic and Cantonese, hmmm, I doubt it.
But then the question arises: whether it is really productive to start with 2 languages at the same time...
If by an adult learner you mean someone with a full time job, social life or, worse yet, family responsibilities, I would defintely curb my enthusiasm even languages are easy or related.
Still too many variables. It's hard to generalize.