In my experience, once you've studied a language for a while/to a certain level of competency, it's like riding a bike. I haven't studied French or Chinese for

In my experience, once you've studied a language for a while/to a certain level of competency, it's like riding a bike. I haven't studied French or Chinese for over a decade, but I can still (for example) read an article in Le Monde. On the other hand, my German and Arabic are basically non-existent while my Latin is somewhere in the middle. Reading comprehension is also the thing that degrades the least in my experience (as long as there's an alphabet; bets are off with languages with Chinese and Japanese Kanji). I can recognize the subjunctif in French, but if I had to use it/conjugate it, I'd just stare blankly at you.