Some people seem to want to learn a language without caring much about the language's grammar. By "grammar", I mean stuff like sentence structure, tenses and conjugation, noun-adjective agreement.
Apart from vocabulary, grammar seems to be sort of the only thing that defines a language. Knowing grammar allows one to identify what the "usual cases" are, and what the "exceptions" are. What I feel, is that if I didn't know the grammar, I would have to rote-learn all the conjugations for each verb independently, each noun-adjective pair independently etc. - which would be a memorization disaster!
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