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Applicants must submit the results of the SAT I or ACT and three subject SAT IIs even if they submit the results of their school leaving exams.
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AP exams are similar to A Levels - forget about them.
Harvard requires three SAT IIs. You can take some APs in addition to but not instead of the three required SAT IIs. I know that the choice of SAT IIs seems limited at first but it's not that bad. You can always take math and most likely a foreign language and then just pick a third one - science, literature or history, you will find one.</p>