单项选择题

A．The professor was not late.
B．The professor was late because of a traffic jam.
C．The professor was not willing to give the lecture.
D．The professor was late because the hall was so crowded.
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填空题
People once thought of the concept of obtaining fresh water from icebergs. But at that time, it was only (26) a joke more appropriate to cartoons than real life. But now it is being considered quite (27) by many nations, especially since scientists have warned that the human race will outgrow its fresh water (28) faster than it runs out of food. Huge masses of ice are a possible source of fresh water that has always been (29) until recently. Three-quarters of the Earth’s fresh water supply is still in the form of ice, a reservoir of fresh water so (30) that it could supply water to all the rivers of the world for 1000 years. Floating on the oceans every year are 7659 trillion tons of ice in ten thousand icebergs that break away from the ice caps of poles. Huge masses of ice that (31) the shallow continental shelf give birth to icebergs throughout the year. Icebergs are formed entirely on land, breaking off when (32) spread over the sea. As they drift away from the area of poles, icebergs sometimes move (33) in a direction opposite to the wind, pulled by sub-surface currents. To capture them and (34) them to parts of the world where they are needed would not be too difficult. The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the moving of fresh water to shore (35) . But even if the icebergs lost half of their volume in the process, the water they could provide would be far cheaper than that produced by removing salt from water.
填空题
People once thought of the concept of obtaining fresh water from icebergs. But at that time, it was only (26) a joke more appropriate to cartoons than real life. But now it is being considered quite (27) by many nations, especially since scientists have warned that the human race will outgrow its fresh water (28) faster than it runs out of food. Huge masses of ice are a possible source of fresh water that has always been (29) until recently. Three-quarters of the Earth’s fresh water supply is still in the form of ice, a reservoir of fresh water so (30) that it could supply water to all the rivers of the world for 1000 years. Floating on the oceans every year are 7659 trillion tons of ice in ten thousand icebergs that break away from the ice caps of poles. Huge masses of ice that (31) the shallow continental shelf give birth to icebergs throughout the year. Icebergs are formed entirely on land, breaking off when (32) spread over the sea. As they drift away from the area of poles, icebergs sometimes move (33) in a direction opposite to the wind, pulled by sub-surface currents. To capture them and (34) them to parts of the world where they are needed would not be too difficult. The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the moving of fresh water to shore (35) . But even if the icebergs lost half of their volume in the process, the water they could provide would be far cheaper than that produced by removing salt from water.
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