单项选择题
A.become a permanent student in the USA B.take up a summer course in the USA C.go to enjoy a tourist's life in the USA D.spend a summer visiting in the USA
A.through first-hand experience B.in the very countries C.through friendships with people D.through various sources of experience
A.outside the place where you study B.outside the United States C.who will ask you to stay longer in the USA D.who will continue to keep in touch with you after you return to your own country