Try As You Might, There’s A Reason It’s Tough To Learn A New Language As An Adult

You can learn basic grammar and vocabulary at any age. That explains my “good enough” French. But there’s also an enormous amount of low-frequency words and syntax that even native speakers might encounter only once a year. Knowing any one of these “occasional” words or phrasings isn’t essential. But in every context — a book, an article or conversation — there will probably be several. They’re part of what gives native speech its richness. – The New York Times