从1964年到1980年，我国在内地的十几个省、自治区开展了一场以战备为中心、以工业交通、国防科技工业为基础的大规模基本建设，称为三线建设。所谓三线，是由沿海、边疆地区向内地划分为三条线：一线指沿海和边疆地区；三线指四川、贵州、陕西、甘肃、湖南、湖北等内地地区，? From 1964 to 1980, our country carried out a large-scale capital construction based on combat readiness and based on industrial transportation and national defense science and technology industry in more than a dozen provinces and autonomous regions in the Mainland, which is called the third-line construction. The so-called third line is divided into three lines by the coastal areas and border areas: the first line refers to the coastal areas and border areas; the third line refers to the interior areas in Sichuan, Guizhou, Shaanxi, Gansu, Hunan and Hubei provinces;