问题：
But this really is a surprise. It must be ten years _____ we last met in Beijing, isn’t it? And now we run into each other in Xiamen.
[ ]
A. since
B. before
C. when
D. that
But this really is a surprise. It must be ten years _____ we last met in Beijing, isn’t it? And now we run into each other in Xiamen.
B. before
C. when
D. that
[ ]
A. since B. before
C. when
D. that
参考答案：