What is the dragon cave sand water of Feng Shui?

What is the dragon cave sand water of Feng Shui? -dragon, refers to the mountain. Point, that is, the selected small area to be used. Sand refers to the use of the mountains around the selected small area, which requires reunion and care. Water refers to the water around the selected small area to be used, and also refers to the low position, including the road, which needs to be surrounded.