题目内容
4.Plant cloning has been an agricultural technique used by farmers and gardeners for centuries.Grafting (嫁接) is a common form of plant cloning.Many plants in nature actually clone themselves and reproduce asexually.Cloned plants are much more predictable than normal plants,so their yield (产量) is more reliable.Cloned plants also reproduce faster,limiting the amount of time between planting and harvesting.It is also often cheaper to produce seeds through cloning than through traditional methods.Plants can essentially be optimized so that farmers or individual growers always have the best seeds available.With more yield at a faster rate,farms can produce more food for more people while decreasing overall costs.
Cloning can be used to wipe out diseases that previously killed off entire fields of crops.This would make plants immune (免疫的) to the kinds of diseases that farmers and gardeners around the world fear each year.Crop failures due to disease and virus could become a thing of the past.Also,plants that are near extinction can be brought back to life through cloning.
Through cloning scientists can develop"super"fruits and vegetables of superior nutritional quality.This could make for a healthier population overall.This is already being done through selective pollination (授粉),and genetic cloning could take it to the next level.
By plant cloning we have a population of identical plants and all these plants equally suffer from the same diseases,but in nature the weak would die and the strong would survive.While there are some dangers to consider with plant cloning,there are plenty of benefits that could prove vital to the propagation (繁衍) of the human species.
29.The underlined word"optimized"in Paragraph 2can be replaced by"C".
A.enlarged
B.produced
C.perfected
D.examined
30.According to the text,cloned plantsD.
A.have lower yield than normal plants
B.need little care from people
C.resist various kinds of diseases
D.have a short growth cycle
31.What is the main purpose of the text?D
A.To warn the negative effects of plant cloning.
B.To present different kinds of plant cloning.
C.To predict the future of plant cloning.
D.To inform us about the advantages of plant cloning.
分析 本文主要介绍了植物克隆的好处.
解答 29.C,词义猜测题,根据so that farmers or individual growers always have the best seeds available"农民和个体种植户总会有最好的种子"可知,optimize与perfect的意思相近.
30.D,细节理解题,从第二段中的Cloned plants also reproduce faster,limiting the amount of time between planting and harvesting可知,克隆的植物的生长有一个短的生长周期,故答案为D.
31.D,写作意图题,本文主要介绍了植物克隆的好处,主要是告诉我们这件事情,故答案为D.
点评 解答任务型阅读理解题,首先对原文材料迅速浏览,掌握全文的主旨大意.因为阅读理解题一般没有标题,所以,速读全文,抓住中心主旨很有必要,在速读的过程中,应尽可能多地捕获信息材料.其次,细读题材,各个击破.掌握全文的大意之后,细细阅读每篇材料后的问题,弄清每题要求后,带着问题,再回到原文中去寻找、捕获有关信息.最后,要善于抓住每段的主题句,阅读时,要有较强的针对性.对于捕获到的信息,要做认真分析,仔细推敲,理解透彻,只有这样,针对题目要求,才能做到稳、准.
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