In fact, if you cut out the speaking part, English is exceedingly simple. The only difficulty in English is pronunciation of written words and in reverse spelling words you hear. The English spelling system is hopelessly broken, making it extremely difficult. If it's just the written part of the language, anyone could learn it. I don't know what kind of exam it was in the chapter, but if it was only the written component, then there's absolutely no reason why she wouldn't ace it. What comes to listening comprehension, I'd imagine a totally hearing impaired person would be exempted from that.