我们居住的地球并不平静,除了时不时地来点地震、火山喷发等,发发威以外,还由于自然和人为等因素,地面还在悄悄地下沉。虽然地球的这个小动作悄无声息,可带给我们的却是不小的大麻烦。它可以将高楼变成楼歪歪甚至楼倒倒;它可以使地面突然出现裂缝;它使平原良田突现天坑;它可以将上海沉入大海;它可以使整个华北平原形成一个下陷的大漏 We live in the earth is not calm, except from time to time to some earthquakes, volcanic eruptions, hair growth, but also because of natural and man-made and other factors, the ground is still quietly sinking. Although this little trick on earth is silent, it is no small inconvenience caused to us. It can turn the tall building into a crooked one or even upside down; it can cause sudden cracks in the ground; it makes the plain fertile land suddenly emerge from the sky; it can sink Shanghai into the sea; it can make the entire North China Plain form a large subsidence