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 (產(chǎn)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 本文主要介紹了植物克隆的好處.
解答 29.C,詞義猜測(cè)題,根據(jù)so that farmers or individual growers always have the best seeds available"農(nóng)民和個(gè)體種植戶總會(huì)有最好的種子"可知,optimize與perfect的意思相近.
30.D,細(xì)節(jié)理解題,從第二段中的Cloned plants also reproduce faster,limiting the amount of time between planting and harvesting可知,克隆的植物的生長(zhǎng)有一個(gè)短的生長(zhǎng)周期,故答案為D.
31.D,寫作意圖題,本文主要介紹了植物克隆的好處,主要是告訴我們這件事情,故答案為D.
點(diǎn)評(píng) 解答任務(wù)型閱讀理解題,首先對(duì)原文材料迅速瀏覽,掌握全文的主旨大意.因?yàn)殚喿x理解題一般沒有標(biāo)題,所以,速讀全文,抓住中心主旨很有必要,在速讀的過程中,應(yīng)盡可能多地捕獲信息材料.其次,細(xì)讀題材,各個(gè)擊破.掌握全文的大意之后,細(xì)細(xì)閱讀每篇材料后的問題,弄清每題要求后,帶著問題,再回到原文中去尋找、捕獲有關(guān)信息.最后,要善于抓住每段的主題句,閱讀時(shí),要有較強(qiáng)的針對(duì)性.對(duì)于捕獲到的信息,要做認(rèn)真分析,仔細(xì)推敲,理解透徹,只有這樣,針對(duì)題目要求,才能做到穩(wěn)、準(zhǔn).