Question

1．As people slowly learn to cure diseases，control floods，prevent hunger，and stop wars，fewer people die every year．As a result，the population of the world is becoming larger．In 1925 there were about 2 billion people in the world； today there are over 6 billion．
When the number rises，extra mouths must be fed．New lands must be brought under development，or land already farmed must be made to produce more crops．In some areas the land is so over-developed that it will be difficult to make it provide more crops．In some areas the population is so large that the land is divided into too tiny units to make improvement possible with farming methods．If a large part of this farming population went into industrial work，the land might be farmed much more productively （多產(chǎn)地） with modern methods．
There is now a race for science，technology，and industry to keep the output of food rising faster than the number of people to be fed．New types of crops，which will grow well in bad weather，are being developed，so there are now farms beyond the Arctic Circle in Siberia and North America．Irrigation （灌溉） and dry-farming methods bring poor lands under the plough．Dams hold back the waters of great rivers，which can provide water for the fields in all seasons and provide electric power for new industries．Industrial chemistry provides fertilizer to suit different soils．Every year，some new methods are made to increase or to protect the food of the world．
48．The author says that the world population is increasing becauseC．
A．there are many rich valleys and large fields
B．farmers are producing more crops than before
C．people are living longer due to better living conditions
D．new lands are being made into farmlands
49．The author says that in areas with large populations，land might be more productively farmed ifC．
A．the land was divided into smaller pieces  
B．people moved into the countryside
C．industrial methods were used in farming  
D．the units of land were much larger
50．We are told that there are now farms beyond the Arctic Circle．This has been made  possible byA．
A．growing new types of crops      
B．irrigation and dry-farming means
C．providing fertilizers             
D．destroying pests and diseases
51．Why do some people use dams to hold back waters from great rivers？C
A．To develop a new kind of dry-farming methods．
B．To prevent crops from floods．
C．To provide water and electricity in all seasons．
D．To water poor lands in bad weather．

Answer 1

分析 本文是一篇說明文，說明了隨著人口的增長，新的土地必須得到發(fā)展或土地耕種必須產(chǎn)生更多的作物．在下文中介紹了通過一些新的農(nóng)耕的方法來提高農(nóng)業(yè)產(chǎn)量，維持人類的生存問題．

解答 48．答案C．細(xì)節(jié)理解題．由第一段的As people slowly learn to cure diseases，control floods，preventhunger，and stop wars，fewer people die every year．As a result，the populationof the world is becoming larger．可知答案選C．
49．答案C．細(xì)節(jié)理解題．由第二段的In some areas the population is so large that the land is dividedinto too tiny units to make improvement possible with farming methods．If alarge part of this farming population went into industrial work，the land mightbe farmed much more productively （多產(chǎn)地） with modern methods．可知如果當(dāng)?shù)匦纬晒�業(yè)性作業(yè)，土地就由于現(xiàn)代化的方法而多產(chǎn)．故選C．
50．答案A．細(xì)節(jié)理解題．由第三段的New types of crops，which will grow well in bad weather，are beingdeveloped，so there are now farms beyond the Arctic Circle in Siberia and NorthAmerica．可知由于新型農(nóng)業(yè)的出現(xiàn)，才導(dǎo)致了北極圈內(nèi)的地區(qū)出現(xiàn)了很多的農(nóng)田．故選A．
51．答案C．細(xì)節(jié)理解題．由最后一段倒數(shù)第四行which canprovide water for the fields in all seasons and provide electric power for newindustries．故選C．

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