Didn't go to school in the U.S., but I did a test in Yr 12 that sounds similar. Multiple choice component on logic, comprehension, vocab, etc, skills, and an essay component. Seemed to me that it was similar to debating in school. They were after a clear, concise argument, with logical backing of your points. I think the time limit was 1 hour, and they were after roughly 500 words. I got straght E's for English all through Yr 11/12, as I didn't bother to turn up or do the assessment all that much. However after we did a trial essay in preparation for the test on a day I was actually there, I got 18/20 and drafted into the school debating team. When we did the actual test I got a similar mark. I'm very ordinary at creative writing, but creative writing isn't what they're looking for. Clear, concise, well reasoned arguments is what they're after.