电信的任何产品都可切割成()、()、()、()和()五个模块。
参考答案:基础产品;系统集成;外包服务;专业服务;知识服务
It is in the hall behind the teaching building ____ we usually have our P.E. lessons on rainy days. [ ]
A. where
B. that
C. which
D. what
25HZ相敏轨道电路分路残压如何测试?