当服务器端或网络的日常维护会导致PMS使用中断时，应提前（）小时发布公告。
A.12
B.24
C.36
D.48
参考答案：D
33×（-2）2﹣（-3）3×（-2）3
We have been in China _____ three years. We like it very much. [ ]
A. in
B. since
C. for
