In 1798 the political economist Malthus predicted that in time mankind would face starvation, having outgrown the available food

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问题     In 1798 the political economist Malthus predicted that in time mankind would face starvation, having outgrown the available food supplies. Today, a century and a half later, there are still experts who forecast the same global disaster unless urgent measures are taken to prevent it.
    By the end of the present century there may well be over five thousand million people living on this globe, ail increase of over fifty per cent of today’s figure. In order to keep pace with this increase in mankind the farmers of the world would have to step up their production of food by at least two per cent every year. Such a rate of increase has never been maintained in any country by conventional methods of agriculture, despite modern mechanization and the widespread use of fertilizers. There are no large worthwhile reserves of potential farmland, remaining, and good fertile land is continually being diverted to industrial use. Moreover, erosion of the soil takes a constant toll.
    Intensive research, carried out over many years in all manner of climatic conditions, has produced a revolutionary method of growing crops without using any soil at all. Hydroponics, as this technique is called, may well be the answer to all our food worries. Already it has accomplished wonders in producing huge crops. Hydroponics was once a complicated and expensive business; now it is well out of the experimental stage. Labor costs are far lower than when normal methods of agriculture are employed. In fact, it is a completely automatic system. There is no hard manual work, no digging or plowing, and no weeding to speak of. Yields can be far higher than they are in soil.
Judging from the passage, the most important advantage of hydroponics should be______.

选项 A、higher yield
B、lower labor costs
C、more automation
D、less hard manual work

答案C

解析 根据文章最后一段倒数第二句。“In fact,it is acompletely automatic system.”可知,从通行情况来看,最重要的水耕优势应该是一个自动的系统。
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