阅读材料：
As early as the twelfth century A.D., the settlements of Chaco Canyon in New Mexico in the American Southwest were notable for their “great houses,” massive stone buildings that contain hundreds of rooms and often stand three or four stories high. Archaeologists have been trying to determine how the buildings were used. While there is still no universally agreed upon explanation, there are three competing theories.
早在12世纪，美国西南部墨西哥地区查科峡谷的居民就以他们的“巨屋”而闻名。这种石质材料建成的“巨屋”包好有数百个房间，而且通常有三到四层高。很多考古学家都试图解释这些建筑的用途。尽管业界尚未达成一致，但现在有三个比较有竞争力的理论。
