Passage 6

　　Water problems in the future will become more intense and more complex. Our increasing population will tremendously increase urban wastes， primarily sewage. On the other hand， increasing demands for water will decrease substantially the amount of water available for diluting wastes. Rapidly expanding industries which involve more and more complex chemical processes will produce larger volumes of liquid wastes， and many of these will contain chemicals which are noxious. To feed our rapidly expanding population， agriculture will have to be intensified. This will involve ever increasing quantities of agricultural chemicals. From this， it is apparent that drastic steps must be taken immediately to develop corrective measures for the pollution problem.

　　But these commonplace generalizations are inadequate： the influence of climate and geography should be studied in depth. Do all mountain dwellers live to a ripe old age？ Doe the drinking of wine， rather than beer， result in a sunny and open temperament？ Is the strength and height of one of the Kenyan tribes due to their habitual drinking of the blood of cows？

　　We are not yet sure of the answers to such questions， bat let us hope that something of benefit to mankind may eventually result from such studies.

　　61. ________ might serve as a suitable title for this selection.

　　A. The Importance of Geographical Environment

　　B. The Influence of Geographical Environment on Man

　　C. Generalization of Types of People

　　D. Geographical Environment， a Mysterious Subject

　　62. Using context clues we may infer that “iodine， fluoride and calcium” are ________.

　　A. substances which an positively or negatively on man‘s health

　　B. harmful substance in the water supply

　　C. substances which help provide breeding places for pests

　　D. substances contributory to good health

　　63. We may infer from the third paragraph that geography and climate play an important role in determining the inhabitants‘________.

　　A. health condition

　　B. personality

　　C. life-span

　　D. all of the above

　　64. According to the author. research into the influence of geography and climate should ________.

　　A. focus on some unknown aspects

　　B. be pursued on a larger scale

　　C. be carried out within a larger scope

　　D. go much deeper

　　65. The author hopes that studies on the influence of geographical environment will enable us to ________.

　　A. generalize better about types of people

　　B. find better water supplies

　　C. gain an insight into its influence on mankind

　　D. lice to a ripe old age