人类上天不容易,挣脱地球引力和冲破大气层,需要强推力火箭和大量的燃料。但其实,人类入地更难,向地下钻虽然不会与地球引力唱对台戏,但是地壳坚硬的岩层是不容易破开的,不仅需要特殊的高级钻头和沙浆的配合,更关键的是,岩石是无法压缩且难以流动的固 It is not easy for mankind to get out of the sky, to get rid of the gravitation of the Earth and to break through the atmosphere. It needs strong thrust rocket and a lot of fuel. However, in fact, it is harder for humans to land in the earth. Although drilling to the underground will not sing on the stage with the gravitation of the earth, rock formations that are hard in the crust are not easy to break apart. Not only do special high-grade drill bits and mortar be used, but more crucially, Uncompressed and difficult to flow solid