填空题. The word conservation has a thrifty meaning. To conserve is to save and protect, to leave what we ourselves enjoy in such good condition as others 1 may also share the enjoyment. Our forefathers had no idea that human population would increase faster than the supplies of crude materials. Most of them, even 2 until very recently, have the foolish idea that the treasures were "limitless" and "inexhaustible". Most of the citizens of early generations knew little or 3 nothing about the complicated and the delicate system that runs all through the nature, which means that, as in a life body, an unhealthy condition of one part 4 will sooner or later be harmful to all others. 5 Fifty years ago nature study was not part of the school work. Scientific 6 forestry was a new idea; timber was still cheap at that time because it could be brought in any quantity from distant woodlands; soil destruction and river floods were not national problems; nobody had already studied long-term climate cycles 7 in relation with proper land use; even the word conservation had nothing of the 8 meaning that it has for us today. For the sake of ourselves and those who come after us, we must now set about 9 repairing the mistakes of our forefathers. Conservation should, however, be made 10 a part of everyone's daily life. To know about the water table in the ground is just as important to us as a knowledge of the basic arithmetic formulas.