一、简要的历史对于人类来说,利用地下空间并不是二十世纪才开始学会的事。早在石器时代,人们就已懂得地下洞穴可用作栖身之所。这里气温常年适中,可不受严寒和酷暑的影响,也可免受风吹雨打之苦。由于种种原因,人类后来才逐渐放弃穴居生活,在地面盖起房子,并逐渐改善了居住条件。就美国的情况来说,虽然在这块土地上人类活动的历史还不长,穴居地下的 First, a brief history For humans, the use of underground space is not the beginning of the 20th century to learn things. As early as the Stone Age, people knew that underground caves could be used as shelter. The temperature here is moderate throughout the year, and it can be protected from the effects of cold and heat, as well as from wind and rain. For various reasons, humans later gradually abandoned burrowing, built houses on the ground, and gradually improved living conditions. In the case of the United States, although the history of human activities on this land is not long, it is underground.