During the Han dynasty, about two thousand years ago, to the north of Huayin Mountain, there lived a family called Yang.

The method has been practically used at the section of Lintong-Huayin of the Wei River and its precision notably increased co…

We went to Huanshan middle school, Huayin in September 1999 and became classmates. We were classmates for three years. That's where we knew each other.