There are times when a small thing like article usage can make a sentence at first make no sense at all or appear to mean something other than it does, but if I read it a couple of times I can understand what the writer is trying to say. I agree with barmaley, I don't find esl learners mistakes nearly as irritating as native speakers. For one thing, the mistakes and els learner makes are different from a native. I guess you grow up believing that anyone who can't get there/their/they're staright is a dumb ass and so it pisses you off to see it. "Their are flowers on they're table" is alot more offensive to me than "A train pulled into station".

So far as your command of english...no natives I know have more than proably an 80% grasp on it. At some point though everthing you say will be correct but it still won't sound 'normal', no one can teach you how to choose words because we all do it differently. Your english is definaly very good though, better than alot of foreigners that live here.