单项选择题
—Hve you been to the United Sttes —Yes, only once. I ________ there only for seven dys.sty
edB.—Hve you been to the United Sttes —Yes, only once. I ________ there only for seven dys.styed B.hd styed C.hve styed D.ws styingA.stayedB.had stayedC.have stayeD.was staying