humans around.

The disappearance of the wolves had many unepected results. Deer and el populations — major food sources () for the wolf — grew rapidly. These animals consumed large amounts of vegetation (植被), which reduced plant diversity in the par. In the absence of wolves, coyote populations also grew quicly. The coyotes illed a large percentage of the par’s red foes, and completely drove away the par’s beavers.

As early as 1966, biologists ased the government to consider reintroducing wolves to Yellowstone Par. They hoped that wolves would be able to control the el and coyote problems. Many farmers opposed the plan because they feared that wolves would ill their farm animals or pets.

The government spent nearly 30 years coming up with a plan to reintroduce the wolvers. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf pacs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. El, deer, and coyote populations are down, while beavers and red foes have made a comebac. The Yellowstone wolf project has been a valuable eperiment to help biologists decide whether to reintroduce wolves to other parts of the country as well. 28. What is the tet mainly about?

A. Wildlife research in the United States. B. Plant diversity in the Yellowstone area. C. The conflict between farmers and gray wolves. D. The reintroduction of wolves to Yellowstone Par.

29. What does the underlined word ＂displaced＂ in paragraph 2 mean? A. Tested.

B. Separated.

C. Forced out.

D. Traced down.

30. What did the disappearance of gray wolves bring about? A. Damage to local ecology. C. Preservation of vegetation.

B. A decline in the par’s income. D. An increase in the variety of animals.

31. What is the author’s attitude towards the Yellowstone wolf project? A. Doubtful. 【答案】

【文章大意】本文是一篇说明文，介绍了美国黄石公园重新引进灰狼的故事。 28. D

【解析】主旨大意题。文章开门见山地提出黄石公园引进灰狼的举措，然后在下文中详细介绍其原因以及带的良好的转机，由此判断本文的中心话题是美国黄石公园重新引进灰狼。

B. Positive.

C. Disapproving.

D. Uncaring.

29. C

【解析】词义猜测题。根据本段后两句可知，因为人类的发展，侵占了灰狼的领域，灰狼逐渐向北迁徙，由此推断灰狼被人类排挤走了。 30. A

【解析】推理判断题。根据第三段的内容可知，灰狼的减少造成了鹿群的增多，从而植被遭到了破坏；土狼的数量快速增加，它们猎杀了大量的赤狐，赶走了海狸，由此可推断出灰狼的消失导致了当地生态平衡被破坏。 31. B

【解析】推理判断题。根据文章末段的最后一句可知，作者认为引进灰狼的项目是很有价值的实验，因此可推知作者对这一举措持肯定的态度。

5. 【2017·全国卷III，D】

The Intelligent Transport team at Newcastle University have turned an electric car into a mobile laboratory named ＂DriveLAB＂ in order to understand the challenges faced by older drivers and to discover where the ey stress points are.

Research shows that giving up driving is one of the ey reasons for a fall in health and well-being among older people, leading to them becoming more isolated(隔绝) and inactive.

Led by Professor Phil Blythe, the Newcastle team are developing in-vehicle technologies for older drivers which they hope could help them to continue driving into later life.

These include custom-made navigation(导航) tools, night vision systems and intelligent speed adaptations. Phil Blythe eplains ＂For many older people, particularly those living alone or in the country, driving is important for preserving their independence, giving them the freedom to get out and about without having to rely on others.＂

＂But we all have to accept that as we get older our reactions slow down and this often results in people avoiding any potentially challenging driving conditions and losing confidence in their driving sills. The result is that people stop driving before they really need to.＂

Dr Amy Guo, the leading researcher on the older driver study, eplains ＂The DriveLAB is helping us to understand what the ey points and difficulties are for older drivers and how we might use technology to address these problems.

＂For eample, most of us would epect older drivers always go slower than everyone else but surprisingly, we found that in 30mph ones they struggled to eep at a constant speed and so were more liely to brea the speed limit

and be at ris of getting fined. We’re looing at the benefits of systems which control their speed as a way of preventing that.

＂We hope that our wor will help with technological solutions(解决方案) to ensure that older drivers stay safer behind the wheel.＂

32. What is the purpose of the DriveLAB? A. To eplore new means of transport. B. To design new types of cars. C. To find out older driver’s problems. D. To teach people traffic rules.

33. Why is driving important for older people according to Phil Blythe? A. It eeps them independent. B. It helps them save time. C. It builds up their strength. D. It cures their mental illnesses.

34. What do researchers hope to do for older drivers? A. Improve their driving sills. B. Develop driver-assist technologies. C. Provide tips on repairing their cars. D. Organie regular physical checups. 35. What is the best title for the tet? A. A new Model Electric Car B. A Solution to Traffic Problems C. Driving Services for Elders D. eeping Older Drivers on the Road

【文章大意】为了了解老年司机所面临的问题，科研人员研制出DriveLAB，目的是能够帮助他们延长驾龄，从而保持积极、健康的生活方式。 32. C

【解析】细节理解题。根据文章首段的内容可知，研制DriveLAB的目的是为了更好地了解老年司机所面临的挑战。 33. A

【解析】推理判断题。根据第四段中 Phil Blythe所说的＂...driving is important for preserving their independence, giving them the freedom to get out and about without having to rely on others＂可知，在Phil Blythe看，能够开车是老年人能够保持独立生活和自由外出的重要条件。 34. B

【解析】推理判断题。根据文章最后三段的内容可知，研究人员希望能够通过研制一些司机辅助技术帮助老年司机延长驾龄、享受更多的独立生活。 35. D

【解析】主旨大意题。文章主要介绍了科研人员通过把电动车改装成一款＂DriveLAB＂研究如何帮助解决老年司机在开车时遇到的问题，以便延长他们独立生活的时间，提高他们的生活质量。 6. 【2017·北京卷，C】

Measles(麻疹), which once illed 450 children each year and disabled even more, was nearly wiped out in the United States 14 years ago by the universal use of the MMR vaccine(疫苗). But the disease is maing a comebac, caused by a growing anti-vaccine movement and misinformation that is spreading quicly. Already this year, 115 measles cases have been reported in the USA, compared with 189 for all of last year.

The numbers might sound small, but they are the leading edge of a dangerous trend. When vaccination rates are very high, as they still are in the nation as a whole, everyone is protected. This is called ＂herd immunity＂, which protects the people who get hurt easily, including those who can’t be vaccinated for medical reasons, babies too young to get vaccinated and people on whom the vaccine doesn’t wor.

But herd immunity wors only when nearly the whole herd joins in. When some refuse vaccination and see a free ride, immunity breas down and everyone is in even bigger danger.

That’s eactly what is happening in small neighborhoods around the country from Orange County, California, where 22 measles cases were reported this month, to Broolyn, N.Y., where a 17-year-old caused an outbrea last year.

The resistance to vaccine has continued for decades, and it is driven by a real but very small ris. Those who refuse to tae that ris selfishly mae others suffer.

Maing things worse are state laws that mae it too easy to opt out(决定不参加) of what are supposed to be required vaccines for all children entering indergarten. Seventeen states allow parents to get an eemption（豁免）, sometimes just by signing a paper saying they personally object to a vaccine.

Now, several states are moving to tighten laws by adding new regulations for opting out. But no one does enough to limit eemptions.