Question

【题目】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（胆怯的）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 2011 through 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 per cent of the less cautious swans presented the same genetic DRD4 variation（变异)while rural swans have different genetic makeups resulting in more wariness(谨慎，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.

【1】The underlined word in paragraph 1 means__________.

A. timid B. cautious

C. bold D. stubborn

【2】What’s the difference between rural swans and urban ones？

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.

【3】What does DRD4 refer to ?

A. a kind of blood. B. a kind of food.

C. a kind of genetic variation. D. a kind of swan.

【4】What does the 4th paragraph mainly talk about?

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.

Answer 1

【答案】

【1】C

【2】C

【3】C

【4】D

【解析】这是 一篇说明文。研究表明城市的天鹅身体内带有一种变异的基因DRD4，这使得它们不太怕人类。

【1】词义猜测题。根据下文的that makes them less fearful of humans可知，这种基因使它们不太害怕人类，所以它们非常的大胆，故选C。

【2】推理判断题。根据第一段Urban swans might be born with a daredevil gene that makes them less fearful of humans, compared with their rural colleagues.可知，与农村的天鹅相比，城市的天鹅不太害怕人类，故选C。

【3】细节理解题。根据第五段中的the same genetic DRD4 variation可知，DRD4是一种变异的基因，故选C。

【4】段落大意题。第四段讲述了澳大利亚的科学家们采集了天鹅的血液样本进行研究，并对它们可以接受人类的距离进行了实验并得出结论，城市的天鹅比农村的天鹅更加胆大，故选D。