题目

阅读理解The loss of naturalland isn't just a problem for the Amazon or the rainforests of Southeast Asia.The United States is losing its forests, grasslands, wetlands, and deserts at atruly startling pace.Between 2001 and 2017,some 97, 124 square kilometers of natural land-around the size of Indiana- weredestroyed in the US to make way for roads, industry, farms, and other signs ofhuman civilization. That's equal to a football field-sized piece of land beinglost every 30 seconds. Some of the most serious losses have been experienced inthe South and Midwest, where human development took ove一矿井深125m，在井口每隔一定时间自由下落一个小球，当第11个小球刚从井口下落时，第1个小球恰好到井底，则相邻两小球下落的时间间隔为多大?这时第3个小球与第5个小球相距多少米?p.14【3】