问题
选择题
--Have you ever been here before?
---Well, I once _________ here for four years. Those days are really unforgettable.
A．have stayed
B．had stayed
C．have been staying
D．stayed
答案
答案：D
考查时态。根据语境及时间状语for four years可知，用一般过去时。句意：——你以前来过这里么？——嗯，我在这里呆过四年，那些岁月真的难忘。