求翻译：远在4000多年前，生活在陕西省北部黄土高原上的人们就有挖穴而居的习俗。窑洞一般高3米多，宽3米左右，最深的可达20米。洞口都朝阳，这样便于阳光照射。最简便的窑洞就是直接挖土形成的窑洞土窑洞；将土窑洞用石头加固，就成石窑洞了，当然，如果用砖加固就是砖窑洞了。砖窑洞外表更美观一些。窑洞这种古老的居住形式和长期以来当地人在生活中形成的窑洞艺术，也吸引着越来越多的外地游客甚至外国人来参观、住宿。是什么意思？

As far away as 4,000 years ago, people living in the northern part of Shaanxi Province on the Loess Plateau, there digging the door to the customs. The cave is the height of three meters, three meters wide, the deepest of up to 20 meters. Hole sun, it is easy to sunlight. The easiest cave excavation

As far back as 4000 years ago, life on the Loess Plateau in northern Shaanxi Province, there is a dug hole, the customs. Cave in general more than 3 m high and 3 meters wide, and the most up to 20 m. Chaoyang hole so that it is easy to have exposure to sunlight. The easiest and the cave that is form

As far as more than 4,000 years ago, people living in loess plateau of Northern Shaanxi Province dug hole and in practice. Cave-General more than 3 meters high, about 3 meters wide, most can be up to 20 meters deep. Entrance is Chaoyang, which makes it easier to sunlight. Easiest cave digging is the