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  3. Scientists have created a tomato that can grow on salty water. The plant is

Scientists have created a tomato that can grow on salty water. The plant is

游客2024-07-03  50
问题     Scientists have created a tomato that can grow on salty water. The plant is the first crop of its kind ever produced in the world.
    Its significance can not be overestimated (高估). The new technology can help mankind solve the problem of feeding its ever-expanding population. It is estimated that by 2025 the world population will amount to more than 9 billion, an increase of 3 billion over 2000. Each day 240,000 more people are born, ready to be fed like the rest of us. Unfortunately, not all the land on Earth can be used to grow crops for humans. About 24.7 million acres of the problem is irrigation (灌溉). When farmers water their crops, salts in the water also enter the soil. Over time, salts such as sodium (钠) and calcium (钙) build up to such a point that they severely harm the growth of crops. Salts destroy most plants’ ability to draw up water through their roots.
    But, the new variety of tomato produced by American and Canadian scientists can store salts in its leaves so that the fruit doesn’t taste salty. Researchers hope this technology will enable areas of poor-quality land to become productive (多产的). And they can feed some of the world’s growing population. [br] What is the population of the world in 2000 according to the passage?
选项 A、About 9 billion.
B、About 6 billion.
C、About 3 billion.
D、About 5 billion.
答案 B
解析 计算题。根据It is estimated that by 2025 the world population will amount to more than 9 billion, an increase of 3 billion over 2000. 可以计算出2000年的人口为60亿，故选B。
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