1 Down syndrome, usually is caused by an extra copy of chromosome 21 (trisomy 21). Characteristics include decreased muscle tone, asymmetrical skull, slanting eyes and mild to moderate mental retardation.  Edward's syndrome, which is the second most common trisomy after Down syndrome. It is a trisomy of chromosome 18.
Guanxi describes the basic dynamic in personalized networks of influence, and is a central idea in Chinese society.
The name Shaanxi means Land west of Shan. ShÇn was the ancient name for the narrow mountain pass where the Yellow River flows from the Loess Plateau down to the North China Plain. It is now the Shanzhou District of Sanmenxia city in Henan Province.his Northern Silk Road is the northernmost of the Silk Roads and is about 2,600 kilometres (1,600 mi) in length. It connected the ancient Chinese capital of Xi'an to the west over the Wushao Ling Pass to Wuwei and emerging in Kashgar before linking to ancient Parthia.