中兴HLR在逻辑上哪几部分组成？
参考答案：
1.No.7信令处理子系统、
2.业务处理子系统、
3.数据处理子系统
4.操作维护子系统组成
He went fishing after he finished ______ his homework.[ ]
A. do
B. does
C. to do
D. doing
