The area of middle and lower reaches of Yangtze Ri  长江中下游

The middle the middle and upper reaches of the Yel  黄河中上游地区

The middle the middle and upper reaches of the Yellow River  黄河中上游地区

elementary school and middle school students  中小学生

students of elementary and middle school  中小学生

Before the Middle of the 19th Century  社交圈; 卟吩(P)

development of the city center and the rural area  城乡发展

development of the rural area  产业化经营

electric network of the rural area  农村电网

elementary and middle school students in the countryside  农村中小学生

in the middle of the night  半夜

north edge of the middle and lower Yangtze area  中下扬子北缘

Structured Study Techniques of the School of Qin  琴乐流派的结构研究法

Students in the middle school and primary school  中小学生

the area of middle reaches of Yellow River  黄河中游地域

the area of the side  侧面积

The area of the stream out side  出汽边面积

the area of the Three Gorges Reservoir  三峡水库区

the definition of the the middle class  概念界定