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  3. British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their w

British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their w

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问题     British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more. Tim Flowers and Tony Yeo, from Sussex University’s School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty. The pair have recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to【C1】______which genes enable some plants to survive salty conditions. The aim is to breed this【C2】______into crops, starting with rice. It is estimated that each year more than 10m hectares of agricultural land are【C3】______because salt gets into the soil and stunts plants. The problem is caused by several factors. In the tropics, mangroves(红树林)that【C4】______swamps and traditionally formed【C5】______to sea water have been cut down. In the Mediterranean, a series of【C6】______have caused the water table to drop, allowing sea water to seep in. In Latin America, irrigation often causes problems when water is【C7】______by the heat, leaving salt deposits behind. Excess salt then enters the plants and prevents them functioning【C8】______. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive. To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little salt and store what they do absorb in cells that do not affect the plants’ growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resulting seeds are ready to be considered for【C9】______use. Once the characteristics for surviving salty soil are known, Flowers and Yeo will try to breed the【C10】______genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.
A)evaporated I)create
B)barriers J)capability
C)normally K)establish
D)economic L)ensure
E)excluded M)capacity
F)lost N)commercial
G)droughts O)appropriate
H)perfectly
【C5】
选项
答案B
解析 分析句子结构可知，所填词在句中作formed的宾语，故应为名词。且该名词能与介词to搭配使用，故可将答案限定在B)barriers、M)capacity中。第2句提示本句是举例说明每年会有10万公顷的农业用地变为盐碱地的原因。本句的定语从句主要讲的是mangroves的作用。结合句子语境及常识可知，mangroves能阻挡海水侵入热带雨林的土壤中，故答案为B)barriers(障碍、屏障)。
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