灵活交流输电技术可以大幅度提高输电线路输送能力，提高电力系统稳定水平，降低输电损耗。
参考答案：对
We went through a period ______ communications were very difficult in the rural areas. [ ]
A. which
B. whose
C. in which
D. with which
简述终端盒成端的种类与方法。
