First of all, look at the compulsory A-level subjects required by the universities and subjects you want to apply for.

If you're not sure.

A level is generally three exams, plus an A.

If you want to take chemistry and mathematics, but you can't choose the other one, you might as well study mathematics again. Anyway, it's all math and level.

In fact, you can also take the A level Chinese exam. . .