【推荐1】New research implies that even a small amount of exercise might do help to older people with light memory problems. Patients have long been advised to do physical activity to help keep their brains healthy. But the U.S. government-supported research marks the longest study of whether exercise makes any difference once memory starts to decline.

Researchers found around 300 inactive older adults with memory changes called mild cognitive impairment (MCI) (轻度认知障碍). In the research, the participants were divided into two groups and half of them did aerobic exercises, while the rest did stretching and balance movements that raised their heart rates a little. After a year, testing of mental activity showed neither group had worsened, said lead researcher Laura Baker of Wake Forest School of Medicine. By comparison, similar MCI patients in another long-term study of brain health — but without exercise       experienced cognitive decline over a year.

Maria Carrillo is the Alzheimer’s Association chief scientific officer. She said earlier research has found regular physical activity of any kind may reduce damaging inflammation and increase blood flow to the brain. She added that the new study is especially interesting because the COVID-19 pandemic began halfway through the study. That meant the study participants became socially isolated. Social isolation has long been known to increase people’s risk of memory problems.

It is a difficult time for dementia (痴呆症) research. Doctors are not sure about prescribing (开处方) a high-priced new drug called Aduhelm. The drug is supposed to be the first to slow the progression of dementia but it is not yet clear if it really helps patients. Researchers last month reported another drug that works similarly failed in an important study. There is growing urgency to find whether exercise might offer at least some protection. Baker will lead an even larger study of older adults to see if adding exercise to other steps such as a healthy diet, brain games and social activities may reduce the risk of dementia.

1. What’s the purpose of the new study?

A．To identify the causes of declining memory in older adults.

B．To explore the influence of exercise on elders’ memory.

C．To develop effective medicines for elders with MCI.

D．To figure out ways to slow the aging process.

2. In which respect were the two groups different in terms of research design?

A．Professional background.

B．Previous physical condition.

C．Diet plan.

D．Exercise type.

3. What attitude does Maria Carrillo hold to the new study?

A．Doubtful.

B．Negative.

C．Positive.

D．Indifferent.

4. According to the last paragraph, what will researchers do next?

A．Conduct further research on how to reduce the risk of dementia.

B．Organize a wide variety of social activities for older people.

C．Develop a new drug to help patients with brain diseases.

D．Find out how to lower the price of Aduhelm.

【推荐2】Climate change, not human hunting, may have destroyed the thylacine(袋狼) , according to a new study based on DNA from thylacine bones.

The meat-eating marsupials (有袋动物) died out on mainland Australia a few thousand years ago, but survived in Tasmania, an island of southeast Australia separated from the mainland, until the 1930s. Until now, scientists have believed the cause of this mainland extinction was increased activity from native Australians and dingoes (Australian wild dogs).

Scientists behind the University of Adelaide study, which was published in the Journal of Biogeography on Thursday, collected 51 new thylacine DNA samples from fossil bones and museum skins. The paper concluded that climate change starting about 4,000 years ago was likely the main cause of the mainland extinction.

The ancient DNA showed that the mainland extinction of thylacines was rapid, and not the result of loss of genetic diversity. There was also evidence of a population crash in thylacines in Tasmania at the same period of time, reducing their numbers and genetic diversity.

Professor Jeremy Austin said Tasmania would have been protected from mainland Australia’s warmer, drier climate due to its higher rainfall. He argued that climate change was “the only thing that could have caused, or at least started, an extinction on the mainland and caused a population crash in Tasmania.”

“They both occurred at about the same time, and the other two things that have been talked about in the past that may have driven thylacines to extinction on the mainland were dingoes and humans. So the only explanation that’s left is climate change. And because that population collapse happened at the same time that the species went extinct on the mainland, our argument is there’s a common theme there and the only common theme is that there is this change in climate.”

1. What did scientists believe in the past according to the passage?

A．Marsupials were all meat-eating animals.

B．Dingoes should be removed from Australia.

C．Thylacines had no enemies on mainland Australia.

D．Human activities may cause the extinction of thylacines.

2. What’s the difference between mainland Australia and Tasmania?

A．Tasmania has more dingoes.

B．Tasmania has more native activities.

C．Tasmania has a higher temperature.

D．Tasmania has more rainy days.

3. What does the underlined word “collapse” in the last paragraph probably mean?

A．change

B．aging

C．decline

D．increase

4. What’s the best title for the passage?

A．The result of warmer climate in Australia

B．The ways of protecting meat-eating animals

C．The cause of disappearance of thylacines

D．The effect of climate change on wildlife

【推荐3】A Colourful Puzzle

People often wear clothing with colours that express something about themselves. A happy person might choose to wear a bright yellow shirt. A swimmer might wear a sea-blue dress.

Animals appear in different colours too, but they don’t get to pick what they wear every morning. Scientists have known for a long time about some of the ways animal colouring can be beneficial. They know that some animals’ colours attract mates or show who is boss. Other animals’ colours blend (融合) in with their environment; thus the animals cannot be seen by their enemies. Still, scientists do not fully understand why blue jays are blue or why rainforest frogs are golden. Now many scientists are working hard to figure out the puzzles of animal colours.

Part of the answer can be found in an animal’s habitat, the place where it lives. It turns out that many animals-especially birds, fish, and reptiles-can see more colours than humans can. These creatures notice colours that stand out in their habitat. For example, forests are mostly green, brown, and yellow. For an animal to be seen by others of its species, it would have to be a different colour than its background. That explains why you can find birds of many shades of blue living in forests.

Another piece of the puzzle lies in what an animal eats. Birds often eat things that have chemicals in them called “carotenoids” (类胡萝卜素). These chemicals are what make tomatoes red and bell peppers bright orange or yellow. When birds eat these foods, the carotenoids affect the colour of their feathers. For example, a cardinal’s bright red feathers will become lighter or darer depending on how many berries it has found to eat.

Some animals do not have any colour at all-but they are not just white; they are transparent (透明的)! Transparent animals live mostly in the ocean. This amazing wonder of nature came about because the animals needed a way to escape their enemies. They are often slow, defenseless creatures that would have no way of fighting back if larger animals wanted to eat them. Because there are few places to hid in the ocean, these creatures have to hide in plain sight. A good example of this kind of transparent creature is the jellyfish. A jellyfish’s body is almost all water, so it is very hard to see it floating in the ocean.

Animals come in all kinds of colours. Their colours are caused by many different factors, and most animals will remain the same colour for their whole lives. Think how lucky we are to get to change our feathers every day!

1. What is the main idea of this text?

A．Animals appear in many different colours.

B．Animals are unable to choose their colours.

C．Animal’ colours are caused by different factors.

D．Animals need colours to blend into their surroundings.

2. According to the text, what is the reason that some animals are transparent?

A．It marks the places they live in.

B．It shows the leader of the group.

C．It helps them to escape enemies.

D．It allows their mates to see them.

3. It can be inferred that why football players wear uniforms during a game is ________.

A．to identify group members	B．to show their personalities
C．to distinguish the group leader	D．to blend in with the environment

4. How is the text mainly organized?

A．By comparisons.	B．Through classification and explanations.
C．In order of events.	D．In order of importance.

【推荐3】Everyone has some opinion about history, no matter how ill-informed．Walking through a parking lot in a university in Miami, I noticed a bumper sticker （车尾贴纸） that said, “Ruin a Liberal’s （自由派） Day—Recite Historical Fact!” But Marwick thinks this sort of opinion is just fine; it is unavoidable that we all feel a sense of ownership of history.
History never stands still, as Marwick says at the beginning of The Nature of History, “The shape and content of history, too, vary according to the methods and materials available to different generations.” Marwick’s goal is to explain, in plain language, the changes in the way history is done up to the present; one method is to connect history with advances in the physical sciences. Marwick examines a number of case studies toward the end of the book. He ends the book with a refreshing collection of aphorisms （格言） about history. History truly belongs to each and every man and we all belong to history; with the proper education, history can be made more accessible to everyone.
Marwick relates how inventions and the physical sciences have driven historical changes. Dropping a ball in a vacuum will reveal the same properties （性质） each time the experiment is conducted, providing the conditions are the same. But historians obviously do not have the luxury of reproducing such conditions; historians view the past through the present which depends on invention and science.
By looking at the changing nature of history, Marwick feels the study progressing. Although Marwick suspects some people would accuse a historian of creating job security with the endless views of the past, he insists it is imperative based on the philosophy, science, and new materials of the age. History, according to Marwick, must be for everyone and not remain locked behind the walls of academia.
1. The author mentions the bumper sticker in order to ________.

A．show his own opinion about history

B．introduce the readers to Marwick

C．explain the freedom of understanding history

D．make the readers know about the argument between historians

2. Which of the following best describes the statement “History never stands still”?

A．Marwick explains the changes in the way history is done up to the present.

B．Marwick connects history with advances in the physical sciences.

C．He ends the book with a refreshing collection of aphorisms about history.

D．The shape and content of history vary according to the methods and materials available.

3. In paragraph 3, Marwick gives the example of dropping a ball in a vacuum to prove ______.

A．the changeable nature of history

B．the difficulty of historical study

C．changeable ways of historical study

D．the difficulty of scientific study

4. The text is intended to ________.

A．state a historian’s ideas

B．argue against a historian

C．attract readers to study history

D．describe the story of a historian