McClatchy Newspapers: Like millions of other Chinese, Li Zhanjun lives in a dwelling that is fireproof, noise proof, warm in winter, cool in summer and the epitome of an eco-friendly design. Moreover, it’s cheap. Li lives in a cave. About 20 million Chinese still reside in caves and dirt-covered dwellings on the Loess Plateau that straddles the middle and upper reaches of the Yellow River in China’s northwest. Some of the caves have been passed down for generations, with hard-packed earthen …