That's awkward. You can become a doctor here after five years of college, but it's exceptionally hard to get into the doctorate schools. Mess up one single highschool grade (in one of the 32-36 classes we take here), and chances are very certain that someone else with better grades than you will steal your spot. There aren't any multiple choice tests or easy way to get good grades at all either, and the final tests only work as a suppliment to your current grades in most cases.

Anyway, studying in advance is a good thing. In fact, if you could somehow get past the thinking of "homework", you'd most definitely do good. Getting to a point where homework isn't "oh fuck, not MORE", but rather "yay, finally something to do, I LOVE studying the string theory in depth" would most definitely get you good grades. And no, you can't force yourself to like it, just try to find a reason for learning it rather than only trying to do well on tests.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram