9.Urban swans might be born with a daredevil gene that makes them less fearful of humans,compared with their rural colleagues.
A study has found swans living in cities tend to be bolder and it is at least partly determined by a gene called DRD4.Birds with this gene could therefore be better adapted to settling in more populated areas,while more timid(膽怯的)swans would escape to less inhabited regions.
It could help to explain why swans in public parks and on urban rivers have a reputation for being so aggressive towards humans-they are simply not afraid of us.
Biologists from some universities in Australia,tracked and collected blood samples from black swans living in two wetlands near cities.One group of swans lived in a recreational urban park,while the other occupied a waste-water processing site out of town.The two areas were less than 20 miles apart.Later,from 2011through 2013,the researchers started systematically scaring the swans at both sites.The researchers approached the birds and calculated how close they could get before they flew away.As expected,they noticed that while rural swans started flying away if a human was closer than 119 meters,the scientists could come as close to urban swans as 39 meters before taking off.
Analyses of the blood samples,in fact,showed that 83 percent of the less cautious swans presented the same genetic DRD4 variation(變異)while rural swans have different genetic makeups resulting in more wariness(謹(jǐn)慎,小心).
The researchers conclude that swans with the bold variation of the gene might choose to live in urban environments,as they tend to be less bothered by human presence.
24.The underlined word in paragraph 1meansC.
A.timid
B.cautious
C.bold
D.stubborn
25.What's the difference between rural swans and urban ones?C
A.The rural swans carry more DRD4.
B.The urban swans are more friendly.
C.The urban swans are less scared of people.
D.The rural swans are aggressive towards humans.
26.What does DRD4 refer to?C
A.a(chǎn) kind of blood.
B.a(chǎn) kind of food.
C.a(chǎn) kind of genetic variation.
D.a(chǎn) kind of swan.
27.What does the 4th paragraph mainly talk about?D
A.The living habit of swans.
B.The living environment of swans.
C.The contribution of the biologists.
D.The process and result of the research.
分析 短文主要講了有DRD4基因的天鵝相對比起沒有這種基因的天鵝更勇敢,更不怕人類,同時這也是鄉(xiāng)下和城市的天鵝的不同之處.
解答 24.C,詞義猜測題,根據(jù)后面定語從句 that makes them less fearful of humans"讓它們不那么害怕人類",可推測該詞的意思是"勇敢的",故答案為C.
25.C,細節(jié)理解題,根據(jù)句子It could help to explain why swans in public parks and on urban rivers have a reputation for being so aggressive towards humans-they are simply not afraid of us可知,鄉(xiāng)下和城市的天鵝最大的不同就是城市的天鵝更不害怕人類,故答案為C.
26.C,細節(jié)理解題,根據(jù)句子with the bold variation of the gene might choose to live in urban environments可知,DRD4指的就是一種基因變異,故答案為C.
27.D,段落大意題,第四段主要講了生物學(xué)家通過研究不同天鵝的血液樣本,并得出結(jié)論,因此這一段主要講的是研究的進程和結(jié)果,故答案為D.
點評 解答任務(wù)型閱讀理解題,首先對原文材料迅速瀏覽,掌握全文的主旨大意.因為閱讀理解題一般沒有標(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,細讀題材,各個擊破.掌握全文的大意之后,細細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,要有較強的針對性.對于捕獲到的信息,要做認(rèn)真分析,仔細推敲,理解透徹,只有這樣,針對題目要求,才能做到穩(wěn)、準(zhǔn).