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 （多产地） 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 本文是一篇说明文，说明了随着人口的增长，新的土地必须得到发展或土地耕种必须产生更多的作物．在下文中介绍了通过一些新的农耕的方法来提高农业产量，维持人类的生存问题．

解答 48．答案C．细节理解题．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．可知答案选C．
49．答案C．细节理解题．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 （多产地） with modern methods．可知如果当地形成工业性作业，土地就由于现代化的方法而多产．故选C．
50．答案A．细节理解题．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．可知由于新型农业的出现，才导致了北极圈内的地区出现了很多的农田．故选A．
51．答案C．细节理解题．由最后一段倒数第四行which canprovide water for the fields in all seasons and provide electric power for newindustries．故选C．

点评 这种阅读理解集中考查了细节题，可采用跳读的方法，根据题干中的关键词快速定位，寻找答案．同时要求考生仔细阅读全文，做好相应的标志，以提高阅读的效率和速度．