I studied in the mainland, but immigrated to Hong Kong. How can I take the college entrance examination in the mainland?

If you haven't cancelled your account, you can take the college entrance examination in the place where your account is located in China as long as you don't mention it yourself.

If you have cancelled your household registration and nationality, you can't take the college entrance examination. You can only enroll in domestic universities through the local college entrance examination in Hong Kong and enroll as an international student.