2．Climate change has caused a rise in sea levels．This has increased the amount of salt in fresh water used on coastal farms．As a result farmers are increasingly unable to use fields close to the sea．
Scientists call this process"salinization．"（盐碱化）But a farmer in the Netherlands is now using a mixture of sea and fresh water to grow healthy and tasty vegetables．Marc Van Rijsselberghe started with an experiment．He put several kinds of plants in saline．
"We put a lot of plants in the fields and then we put them in fresh water and in sea water，and then we see which variety is surviving and which variety is dying．"
Mr．Van Rijsselberghe worked on the project with scientists from the Free University of Amsterdam．He divided a farm into eight irrigated areas．Separate pipes pumped fresh and sea water，and a computer program created water with eight levels of salinity．Computerized measuring devices called"sensors"controlled the water levels and the levels of salinity．Mr．Van Rijsselberghe says he was able to harvest vegetables from most of the eight test areas．He says the vegetables were smaller than those grown in fresh water．But he says they also have more sugar and salt，so they taste better．
The farmer grew carrots，cabbage，onions and beetroot．But he found that potatoes grew better than the other vegetables in the combination of sea and fresh water．Mr．Van Rijsselberghe says four kinds of these potatoes were recently sent to Pakistan，where thousands of hectares of land have been damaged by salinization．Farmers in Pakistan will test the Dutch potatoes to see if they can be grown in those fields．
28．What's the purpose of the author mentioning the climate change in the first paragraph？B
A．To show the reason for a rise in sea levels．
B．To introduce the topic of the passage．
C．To tell readers the amount of salt in sea water has increased．
D．To tell readers that farmers are unable to use fields close to the sea．
29．What's"salinization"？D
A．There is much salt in fresh water．
B．There is the most salt in fresh water．
C．There is less salt in fresh water．
D．There is more and more salt in fresh water．
30．From the passage we can learn thatD．
A．Marc conducts the experiment all by himself
B．the vegetables have more salt than sugar
C．carrots grow well，as was expected
D．the experiment is to find out which variety is more suitable for sea water
31．Why were potatoes recently sent to Pakistan？B
A．Because Pakistan lacks potatoes．
B．Because Pakistan has also been damaged by salinization．
C．Because potatoes are in great demand in Pakistan．
D．Because the people in Pakistan like eating more potatoes．
分析 本文是一篇说明文，讲述了世界各地由于土地盐碱化，很多植物都不能存活．科学家们通过实验，找出能在海水里种植的农作物，来克服土地盐碱化造成的损失．
解答 28～31．BDDB
28．B 考查文章主旨．说明文通常将文章主题放在开头的第一段，所以作者在第一段提到气候变化的目的是为了引入文章主题．故选B．
29．D 考查细节理解．根据"This has increased the amount of salt in fresh water used on coastal farms"可知，盐碱化是指水中含盐量增加．故选D．
30．D 考查推理判断．根据"We put a lot of plants in the fields and then we put them in fresh water and in sea water，and then we see which variety is surviving and which variety is dying"可知，这个实验是为了找出哪个品种更适合在海水里生长．故选D．
31．B 考查细节理解．根据"these potatoes were recently sent to Pakistan，where thousands of hectares of land have been damaged by salinization"可知，巴基斯坦的土地也被盐碱化所破坏．故选B．
点评 阅读理解考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
