Questions 26 to 30 are based on the following passage:
　　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 the 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; 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 (水位) in the ground is just as important to us as a knowledge of the basic arithmetic formulas. We need to know why all watersheds (上游源头森林地带集水区) need the protection of plant life and why the running current of streams and rivers must be made to yield their full benefit to the soil before they finally escape to the sea. We need to betaught 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 above the earth. In brief, it should be our goal to restore as much of the original beauty of nature as we can.
　　26. The author's attitude towards the current situation in the exploitation of natural resources is .
　　A) critical
　　B) neutral
　　C) positive
　　D) suspicious
　　27. According to the author, the greatest mistake of our forefathers was that .
　　A) they had no idea about scientific forestry
　　B) they were not aware of the significance of nature study
　　C) they had little or no sense of environmental protection
　　D) they had no idea of how to make good use of raw materials
　　28. It can be inferred from the third paragraph that earlier generations didn't realize .
　　A) the importance of the proper use of land
　　B) the value of the beauty of nature
　　C) the harmfulness of soil destruction and river floods
　　D) the interdependence of water, soil, and living things
　　29. To avoid the mistakes of our forefathers, the author suggests that .
　　A) we plant more trees
　　B) we return to nature
　　C) natural sciences be taught to everybody
　　D) environmental education be directed toward everyone
　　30. What does the author imply by saying “living space...is figured...also in cubic volume above the earth” (Para. 3, Lines 8-10)?
　　A) We need to take some measures to protect space.
　　B) Our living space should be measured in cubic volume.
　　C) Our living space on the earth is getting smaller and smaller.
　　D) We must preserve good living conditions for both birds and animals.