Ocean water plays an indispensable role in supporting life. The great ocean basins hold about300 million cubic miles of water. From this vast amount, about 80,000 cubic miles of water are sucked into the atmosphere each year by evaporation and returned by precipitation and drainage to the ocean. More than 24,000 cubic miles of rain descend annually upon the continents. This vast amount is required to replenish the lakes and streams, springs and water tables on which all flora and fauna are dependent. Thus, the hydrosphere permits organic existence.The hydrosphere has strange characteristics because water has properties unlike those of any other liquid. One anomaly is that water upon freezing expands by about 9 percent, whereas most liquids contract on cooling. For this reason, ice floats on water bodies instead of sinking to the bottom. If the ice sank, the hydrosphere would soon be frozen solidly, except for a thin layer of surface melt water during the summer season. Thus, all aquatic life would be destroyed and the interchange of warm and cold currents, which moderates climate, would be notably absent.Another outstanding characteristic of water is that water has a heat capacity which is thehighest of all liquids and solids except ammonia. This characteristic enables the oceans to absorb and store vast quantities of heat, thereby often preventing climatic extremes. In addition, water dissolves more substances than any other liquid. It is this characteristic which helps make oceans a great storehouse for minerals which have been washed down from the continents. In several areas of the world these minerals are being commercially exploited. Solar evaporation of salt is widely practiced, potash is extracted from the Dead Sea, and magnesium is produced from sea water along the American Gulf Coast.Câu 46: The author’s main purpose in this passage is to _.A. explain how water is used in commerce and industryB. compare water with other liquidsC. illustrate the importance of conserving waterD. describe the properties and uses of waterCâu 47: According to the passage, fish can survive in the oceans because _.A. they do not need oxygenB. ice floatsC. evaporation and condensation create a water cycleD. there are currents in the oceansCâu 48: The word “outstanding” in paragraph 3 is closest in meaning to _ .A. exceptionally good B. special C. important D. amusingCâu 49: According to the passage, the hydrosphere is NOT _.A. a source of natural resources B. the part of the earth covered by waterC. responsible for all forms of life D. in danger of freezing overCâu 50: The word “replenish” in paragraph 1 can best be replaced by __ _.A. replace B. evaporate C. fill again D. formCâu 51: The phrase “This vast amount” in line 4 refers to _.A. 80,000 million cubic miles of water B. 300 million cubic miles of waterC. 24,000 cubic miles of rain D. 80,000 cubic miles of waterCâu 52: The author’s tone in the passage can best be described as _ .A. speculative B. dogmatic C. biased D. dispassionateCâu 53: Which of the following statements would be most likely to begin the paragraph immediately following the passage?A. Another remarkably property of ice is its strength.B. Water has the ability to erode land.C. Droughts and flooding are two types of disasters associated with water.D. Magnesium is widely used in metallurgical processes.Câu 54: The author organizes the passage by __ _.A. juxtaposition of true and untrue ideas B. hypothesis and proofC. general statements followed by examples D. comparison and contrastCâu 55: Which of the following is NOT mentioned as a characteristic of water?A. Water contracts on cooling. B. Water can absorb heat.C. Water is a good solvent. D. Water expands when it is frozen.Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions from 56 to 65.Câu 56: The eldest one of his three daughters has graduated f
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