1) Are you going to study in USA?
2) How long will you study in USA?
3) Why do you want to study in USA?
4) Why do you want go to the United States for further study? (if the accent is on "United States")
5) Many universities in the China offer first--rate graduate programs in xxx. Why do you want to go to the USA for graduate study?
6) When are you going to enter US?