actually, essay in GP would require that you learn how to bring
your point across...
what you need to do is to read a lot more, come up with differing
perspectives, argue your point, make a conclusion about the
topic..
all the time, having good grammar, sentence structure, ability to
make your points systematically and all that...
as for comprehension, i can't help you coz in my time, i've always
failed that part miserably 
good luck!
