(急問)中七美國升學---持有綠卡...........20點!!!

You could study in college before transferring to university.
When I first came to the US, I just finished my F5 mod exam in HK.
They put me back to high school as the education dept said I didn't
finish F6 & F7, comparatively the 11th and 12th grade in the US.
As for your case, they should have considered you'd completed
high school in HK. In US, before you graduate from high school, you
need to take the SAT. Since you are in HK, it doesn't hurt to take the
TOEFL and bring it over. Both university and college accept TOEFL.
In 4-year-college, they have ESL (English as second language) class.
You could pick up your English there. Afterward, you could decide
which major you like. Each university has their own system. Therefore,
you need to check with the admission office in the university and see
which course credits could be transfered.
In the US, it is very easy to get an A in high school. Therefore, you will
find it unfair for them to use your grades on your HK report cards to decide
wheather they will let you study in their university. Hmm, again, that
depends which university you want to apply. It is easier to get started in
college. Their requirement is relatively lower. Usually in college, they
will provide a placement test and see how well you do with Maths and
English. The better you do on the test, the less basic course (English and
Maths) you need to take. The college I went to won't allow student take
any major course until they finish the basic Maths and English courses.
You should registor no later than August. Courses usually start at the 1st
week of September.
Good luck!

Hope this help.

I don't know how do you maintain your green card status. As for Permanent
Residents (green card holders), you should be returning to U.S. every 6 months,
and even that, US immigration department has rights to question your intention
to reside in the US. Given that you go to high school in HK, I don't know how
you can explain to US immigration you had intention to live in the US. In the
worst scenario, US immigration
has rights to void and collect your G.C. as you enter US. If you are a US citizen,
then you don't have any problem. Be careful. As for the alternatives for education,
it has been answered rather well by the other person, I won't repeat.