单选题 The word conservation has a thrifty (节俭的) 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 (祖先) had no idea that human population would increase faster than the supplies of raw (天然的) 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 the complicated (复杂的), 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; nobody had yet studied long-term climatic cycles in relation to proper land use; even the word "conservation" had nothing of the meaning that it has for us today.
For the sake of ourselves and those who will come after us, we must now set about repairing the mistakes of our forefathers. Conservation should, therefore, be made 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. We need to know why all watersheds need the protection of plant life and why the running current of streams and rivers must be made to benefit the soil fully before they finally escape to the sea. We need to be taught the duty of planting trees as well as of cutting them. We need to know the importance of big, mature trees, because living space for most of man's fellow creatures on this planet is figured not only in square measure of surface but also in cubic volume(立方)above the earth. In brief, it should be our goal to restore as much of the original (原始的) beauty of nature as we can.

单选题 The author's attitude towards the present situation in the use of natural resources is______.
A. positive (支持的) B. neutral (中立的)
C. suspicious (怀疑的) D. critical (批评的)

单选题 According to the author, the greatest mistake of our forefathers was that______.
A. they had no idea about scientific forestry
B. they had little or no sense of environmental protection
C. they did not know the importance of nature study
D. they had no idea of how to make good use of raw materials

单选题 With a view to correct the mistakes of our forefathers, the author suggests that______.
A. we plant more trees
B. we be taught environmental science, as well as the science of plants
C. environmental education be directed toward everyone
D. we return to nature

单选题 What does the author imply by saying "living space.., is figured.., also in cubic volume above the earth" in the third paragraph?
A. Our living space on the earth is getting smaller and smaller.
B. Our living space should be measured in cubic volume.
C. We need to take some measures to protect space in volume.
D. We must create better living conditions for both birds and animals.