First of all, which area of South China University of Technology is better? Generally speaking, the difficulty of admission won't make you too nervous. I have a friend who studies chemical engineering there. As far as we know, the difficulty will be basically the same as that of chemical engineering. As for the second interview, it is an old topic. It can be said that if you are good enough, don't be afraid of other factors. You can strive for your best performance then. If you decide, work hard. Good luck and come on.