You learn the international trade has a little bias, in fact, the international trade of the main professional courses is the English language, science and technology foundation basically do not need. With your science and engineering foundation to learn international trade really some yielding ~ economics of the profession is more biased text, often to write papers and so on, to your language ...... Oh afraid you will be very resentful!
If you are interested in the economy you can learn financial engineering, this door is very high on the math requirements, basically pure science majors.
Or you can go to study insurance, actuaries are in short supply in the country, actuarial science is the only requirement is good at math, basically math majors.
There is also, you can undergraduate math, graduate students in the study of finance and insurance. In fact, undergraduate education is basically basic education, if you learn math future development prospects are very good
I think the audit is good, there are prospects and can use your math.
Additionally pure math is not useless, if you are more down-to-earth character, you can consider staying in school later to do research, there is no question of a way out.
Computer science is also very good, but it's a bit flooded right now. It's good to find a job, but the quality of the work is not very hard to guarantee.
Biology is actually a promising major, and bioengineering is not at all the same as medicine, much less anatomy.
Engineering is something I like a lot myself (though not what I'm studying now.) , and the outlook is good.
Your grades can be considered:
Better: Fudan, Jiaotong University, Tongji, Nankai, ZJU, KU, Beipiao, Beihang, etc....
(Depends on this year's first book line...)
Or you can consider applying to colleges in Hong Kong.