[单项选择] The word conservation has a thrifty(节俭) meaning. To conserve is to save and protect, to leave what we ourselves enjoy in such good condition that others may also share the enjoyment. Our forefathers had no idea that human population would increase faster than the supplies of raw materials; most of them, even until very recently, had the foolish idea that the treasures were "limitless" and "inexhaustible". Most of the citizens of earlier generations knew little or nothing about complicated and delicate system that runs all through nature, and which means that, as in a living body, an unhealthy condition of one part will sooner or later be harmful to all the others. Fifty years ago nature study was not part of the school work; scientific forestry was a new idea; timber was still cheap because it could be brought in any quantity from distant woodlands; soil destruction and river floods were not national problems; people had hardly studied long-term climatic cycles in relation to
A. positive
B. natural
C. suspicious
D. critical

[单项选择] The word conservation has a thrifty(节俭) meaning. To conserve is to save and protect, to leave what we ourselves enjoy in such good condition that others may also share the enjoyment. Our forefathers had no idea that human population would increase faster than the supplies of raw materials; most of them, even until very recently, had the foolish idea that the treasures were "limitless" and "inexhaustible". Most of the citizens of earlier generations knew little or nothing about complicated and delicate system that runs all through nature, and which means that, as in a living body, an unhealthy condition of one part will sooner or later be harmful to all the others. Fifty years ago nature study was not part of the school work; scientific forestry was a new idea; timber was still cheap because it could be brought in any quantity from distant woodlands; soil destruction and river floods were not national problems; people had hardly studied long-term climatic cycles in relation to
A. they had no idea about scientific forestry
B. they had little or no sense of environment protection
C. they were not aware of the significance of nature study
D. they had no idea of how to make good use of raw materials

[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 (53)______
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 (54)______
until very recently, have the foolish idea that the treasures were "limitless"
and "inexhaustible". Most of the citizens of early generations knew little or (55)______
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 (56)______
will sooner or later be harmful to all others. (57)______
Fifty years ago nature study was not part of the school work. Scientific (58)______
forestry was a new idea; timber was still cheap