2 . A world in which extinct creatures could be brought back to life came a step closer yesterday. Australian scientists have managed to extract a gene from a preserved sample of a Tasmanian tiger and make it active. The breakthrough has left them dreaming that one day they will be able to recreate the animal, which died out more than 70 years ago. And if it can be done with the Tasmanian tiger, it may also be possible to resurrect (复活) creatures that have been extinct for far longer.

“There used to be a time when extinction meant forever, but no more, ” said Professor Mike Archer. “We are now able to seriously challenge whether those animals that have gone for ever. What has been achieved is a very important step in bringing back those animals that are extinct. And while I think that technically it is still pretty difficult at the moment, we can now see the possibilities. I’m personally convinced that the Tasmanian tiger will be brought back to life in my lifetime.”

The breakthrough came after nine years of experiments by scientists at the University of Melbourne, who extracted a gene from one of several tigers preserved in alcohol in a Melbourne museum. They removed the equivalent gene from a mouse embryo implanted the tiger gene and then watched as the mouse continued to grow normally, suggesting the tiger gene had been activated.

Team leader Dr. Andrew Pask said it was the first time DNA from an extinct species had been used to “induce (引起) a functional response in another living organism”.

However, the animal’s entire gene structure would have to be revived in the same way to even begin the possibility of bringing the Tasmanian tiger back from the dead.

Mick Mooney, a wildlife officer of the Tasmanian Government, was worried that such developments could encourage people’s indifference to the protection of endangered species.

“If people think that we can bring animals back to life after they’ve gone, they will start saying that there is nothing to worry about because we can fix it up later.”

1. What does the underlined word “breakthrough” in the l paragraph refer to?

A．Scientists have recreated new animals.

B．Scientists have resurrected endangered animal.

C．It has turned out that some creatures would not go extinct.

D．A tiger gene has been extracted successfully and activated.

2. Scientists are carrying out the experiments in order to ________.

A．bring extinct animals back to life

B．transplant the genes of tigers into other animals

C．find out what factors lead to the animals’ extinction

D．find a new way to extract animals’ DNA

3. Mike Archer thinks that ________.

A．scientists now have no technological difficulty   reconnecting extinct animals

B．it’ll be a century or so before a Tasmanian tiger walks on the earth again

C．humans have come closer in reconnecting extinct animals

D． reconnecting extinct animals is impossible

4. We can learn from Mick Mooncy’s words that_________.

A．he thought it unnecessary to worry about endangered animals

B．his opinion is in contrast with that of the Tasmanian Government

C．he thought people should be encouraged to protect endangered animals

D．he is concerned that bringing extinct animals back to life may have a negative effect

3 . When you walk on a sandy beach, it takes more energy than striding down a sidewalk — because the weight of your body pushes into the sand. Turns out, the same thing is true for vehicles driving on roads. The weight of the vehicles creates a very shallow indentation (凹陷) in the pavement (路面) — and it makes it such that it’s continuously driving up a very shallow hill.

Jeremy Gregory, a sustainability scientist at M.I.T. and his team modeled how much energy could be saved — and green-house gases avoided — by simply stiffening (硬化) the nation’s roads and highways. And they found that stiffening 10 percent of the nation’s roads every year could prevent 440 megatons of carbon dioxide equivalent emissions over the next five decades — enough to offset half a percent of projected transportation sector emissions over that time period. To put those emissions savings into context — that amount is equivalent to how much CO2 you’d spare the planet by keeping a billion barrels of oil in the ground — or by growing seven billion trees — for a decade.

The results are in the Transportation Research Record.

As for how to stiffen roads? Gregory says you could mix small amounts of synthetic fibers or carbon nanotubes into paving materials. Or you could pave with cement-based concrete, which is stiffer than asphalt (沥青).

This system could also be a way to shave carbon emissions without some of the usual hurdles. Usually, when it comes to reducing emissions in the transportation sector, you’re talking about changing policies related to vehicles and also driver behavior, which involves millions and millions of people — as opposed to changing the way we design and maintain our pavements. That’s just on the order of thousands of people who are working in transportation agencies. And when it comes to retrofitting (翻新) our streets and highways — those agencies are where the rubber meets the road.

1. Why does the author mention “walk on a sandy beach” in paragraph 1?

A．To present a fact.	B．To make a contrast.
C．To explain a rule.	D．To share an experience.

2. What suggestion does the author give to reduce CO2 emissions?

A．Hardening the road.	B．Keeping oil in the ground.
C．Growing trees for decades.	D．Improving the transportation.

3. What is the advantage of this suggestion?

A．Gaining more support.	B．Consuming less money.
C．Involving more people.	D．Facing fewer usual obstacles.

4. What does the underlined part mean in the last paragraph?

A．Those agencies are likely to make more rules.

B．Those agencies will change some related policies.

C．Those agencies might put more rubber tires on the roads.

D．Those agencies will play a key role in making this happen.

4 . Shining just 12 light-years from Earth, the star Tau Ceti so resembles the sun that it has appeared in numerous science- fiction stories and was the first star astronomers ever searched for signs of intelligent life, half a century ago. In 2012 Tau Ceti grew still more interesting when astronomers reported five possible planets somewhat larger than Earth circling closer to the star than Mars orbits (围绕……运动) the sun—one of which is in the star’s habitable zone. Newly released images taken by the Herschel Space Observatory provide even more insight about Tau Ceti’s solar system: greater detail about its dust belt.

Dust arises when asteroids and comets (小行星和彗星) crash into one another, so its location reveals where these dust- creating objects—which are too small to be seen directly—orbit a star. In Tau Ceti’s case, “it’s quite a wide dust belt,” says Samantha Lawler of the University of Victoria in British Columbia. As her team reported in November, the belt’s inner edge is roughly two to three astronomical units (AUs) from the star, which is the position of our own sun’s asteroid belt. (An AU is the distance from Earth to the sun.) Tau Ceti’s dust belt extends out to 55 AU, which would be just beyond our system’s main Edgeworth-Kuiper belt, the zone of small bodies whose largest member is probably Pluto. Presumably full of asteroids and comets, Tau Ceti’s dust belt most likely lacks a planet as large as Jupiter, Lawler says. The gravity of such a massive planet would have driven away most small space rocks.

Within a year a new series of radio telescopes in Chile called ALMA should provide a sharper view of the disk, especially of its inner edge. The ALMA images will help astronomers confirm whether the star’s five proposed planets are indeed real. If the disk overlaps the planets’ hypothesized (假设的) orbits, then they probably do not exist; they would have kept away most asteroids near the star, removing the source of dust.

If those planets do exist, however, Lawler’s team suggests that Tau Ceti’s planetary system may resemble what our solar system would have looked like had the four giant planets—Jupiter, Saturn, Uranus and Neptune- never formed: small planets orbiting close to the star, and nothing but asteroids, comets and dust beyond.

1. According to astronomers, the five possible planets of Tau Ceti________.

A．resembled Earth in size

B．functioned like a solar system

C．were located in Tau Ceti’s habitable zone

D．were nearer to Tau Ceti than Mars to the sun

2. Which of the following is true of Tau Ceti’s dust belt?

A．It is narrower than the asteroid belt in our system.

B．The bodies inside it are all smaller than Jupiter.

C．The gravity of Tau Ceti makes it get denser.

D．It is over 55 astronomical units in width.

3. According to the passage, the five planets are most likely to exist if________.

A．they don’t move into the dust belt while orbiting Tau Ceti

B．they have kept away most asteroids and comets

C．they don’t crash into any asteroid or comet

D．they can be seen clearly by ALMA

4. It can be inferred from the passage that Tau Ceti’s dust belt________.

A．is useful because it stops asteroids or comets crashing into the star

B．makes Tau Ceti different from the sun because it extends farther

C．is interesting because it keeps other planets away from Tau Ceti

D．plays a role in helping decide whether the five planets are real

5 . For millions of years, Arctic sea ice has expanded and shrunk in a rhythmic dance with the summer sun. Humans evolved in this icy world, and civilization relied on it for climatic, ecological and political stability. But now the world comes ever closer to a future without ice. The National Snow and Ice Data Center reported that 2019’s minimum arctic sea ice extent was the second lowest on record. Arctic summers could become mostly ice-free in 30 years, and possibly sooner if current trends continue. As the northern sea ice declines, the world must unite to preserve what remains of the Arctic.

Although most people have never seen the sea ice, its effects are never far away. By reflecting sunlight, Arctic ice acts as Earth’s air conditioner. Once dark water replaces brilliant ice, Earth could warm substantially, equivalent to the warming caused by the additional release of a trillion tons of carbon dioxide (CO₂) into the atmosphere and declining sea ice threatens wildlife, from the polar bear to algae that grow beneath the sea ice, supporting the large amount of marine life.

To avoid the consequences the scientific community should advocate not just for lowering greenhouse gas emissions, but also for protecting the Arctic from exploitation. The Antarctic shows the way. In the 1950s, countries raced to claim the Antarctic continent for resources and military installations. Enter the scientists. The 1957-1958 International Geophysical Year brought together scientists from competing countries to study Antarctica, and countries temporarily suspended their territorial disputes (争议). In 1959, 12 countries signed the Antarctic Treaty to preserve the continent for peaceful scientific discovery rather than territorial and military gain.

Sixty years later, we must now save the Arctic. A new Marine Arctic Peace Sanctuary (MAPS) Treaty would protect the Arctic Ocean as a scientific preserve for peaceful purposes only. Similar to Antarctica, MAPS would prohibit resource exploitation, commercial fishing and shipping, and military exercises. So far, only 2 non-Arctic countries have signed MAPS; 97 more need to sign on to enact it into law. Scientists can help—just as they did for the Antarctic—by giving statements of support, asking scientific organizations to endorse (支持) the treaty, communicating the importance of protecting the arctic to the public and policy-makers, and above all, by convincing national leaders to sign the treaty. In particular, Arctic nations must agree that recognizing the arctic as an international preserve is better than fighting over it. In 2018, these countries successfully negotiated a 16-year moratorium on commercial fishing in the Arctic high seas, demonstrating that such agreements are possible.

Humans have only ever lived in a world topped by ice. Can we now work together to protect Arctic ecosystems, keep the northern peace, and allow the sea ice to return?

1. What can be inferred from the passage?

A．wildlife relies on sea ice for food and water.

B．The Arctic would be ice-free in 30 years.

C．Sea ice slows down the global warming.

D．The melting of sea ice releases CO2.

2. The Antarctic is mentioned in the passage in order to ________.

A．remind readers of the past of the Antarctic

B．propose a feasible approach for the Arctic

C．stress the importance of preserving sea ice

D．recall how the Antarctic Treaty came into being

3. The word “moratorium” (in paragraph 4) is closest in meaning to ________.

A．battle	B．ban
C．memo	D．protection

4. Which of the following might be the best title of the passage?

A．Antarctic: a Successful Comeback?	B．Sea Ice and Global Warming
C．Arctic: the Earth’s Future	D．Life Without Ice?

7 . If you’ve ever had a dog, you know just how deep a connection you can develop with “man’s best friend”. But a dog has a much shorter life span — about 12 to 15 years long — than humans, which means every dog owner has to go through the heartbreaking moment when their loving pet passes away.

Why not make a clone of that dog then? This is the solution offered by a South Korean company, Sooam Biotech Research Foundation. The company has successfully cloned at least 400 dogs, mostly for US customers, ever since it pioneered the technique in 2005. Now, Sooam Biotech is planning to introduce their business to UK dog owners, offering them dogs that look just like their lost ones.

Meanwhile, another dog is selected to supply an egg. Researchers then replace the DNA in the egg with that from the skin cell and implant the egg into the womb (子宫) of a female dog. The egg grows into a puppy over the following two months. To clone a dog, researchers first need to take a skin cell from a living dog or one that has just died.

The whole process takes less than a day, but it comes at a shockingly high price — around £63,000 (614,000 yuan). But if you can’t afford it now, you can also save the cells in a laboratory and access them at a later date. Just like identical twins of humans, they share the exact same DNA but there will still be small differences between them. “The spots on a Dalmatian clone will be different, for example,” Insung Hwang, head of Sooam Biotech, told The Guardian. However, as magical as cloning might sound, there is no guarantee that the cloned dog will be a perfect replica of the original one.

Dog owners will also have to accept the fact that personality is not “clone-able”. Apart from genes, personality is also determined by upbringing and environment, which are both “random elements [that] cloning technologies simply cannot overcome”, Professor Tom Kirkwood at Newcastle University, UK, told The Telegraph.

Perhaps bringing our dogs back with cloning is not the best way to remember them after all.

Kirkwood, a dog owner himself, pointed out: “An important aspect of our relationship with them is coming to terms with the pain of letting go.”

1. According to the article, Sooam Biotech Research Foundation is ______.

A．working on plans to help dog owners enjoy their pets longer

B．offering a way to help dogs give birth to more puppies

C．providing a service that will make copies of pet dogs

D．introducing a completely new technique to clone dogs

2. Which of the following statements about dog cloning is TRUE according to the article?

A．Dog cloning technology hadn’t been put into practice until recently.

B．Dog cloning is very expensive and usually takes several months to complete.

C．Dog cloning is very popular among US and UK pet owners.

D．Cloned dogs might develop different habits and characteristics even though they look very similar.

3. Which of the following shows the correct order of the dog cloning process?
a. an egg is taken from another dog
b. a skin cell is taken from the pet dog and saved in a laboratory
c. the egg is placed in the womb of a female dog
d. the DNA of the egg is replaced by the DNA from the skin cell
e. the egg grows into a puppy in two months

A．acbde.

B．adbce.

C．bacde.

D．badce.

4. We can learn from the article that Kirkwood ______ dog cloning.

A．disapproves of

B．supports

C．is afraid of

D．is curious about

8 . Rain is vital to life on Earth. However, rain isn’t just made of water anymore—it’s partly made of plastic.

Millions of tiny pieces of plastic, called microplastics, are wandering around Earth’s atmosphere and traveling across entire continents, according to a study published in the journal Proceedings of the National Academy of Sciences on April 12. Another study, published in the journal Science in June 2020, has revealed that every year more than 1,000 tons of the particles (颗粒)—equivalent to over 120 million plastic bottles—fall in rain.

Microplastics are plastic particles less than 5 millimeters in diameter (直径) and come from a number of sources. Plastic bags and bottles released into the environment break down into smaller and smaller bits. Some microplastics are manufactured deliberately to provide abrasion (研磨) in a host of products, such as toothpaste and cleansers, according to the Daily Mail. Another major source is your washing machine. When you wash synthetic (合成的) clothing, tiny microfibers get flushed (冲掉) away with the wastewater. Even though the water is treated by a wastewater plant, the microplastics remain, and they are released into the sea, according to American magazine Wired.

Plastic rain may remind people of acid rain, but the former is far more widespread and harder to deal with. The tiny particles, too small to be seen with the naked eye, are collected by the wind from the ground. They are so light that they stay in the air to be blown around the globe. As they climb into the atmosphere, they are thought to act as nuclei (核心) around which water vapor (水蒸气) condenses (凝结) to form clouds. Some of the dust falls back to land in dry conditions, while the rest comes down as rain, according to the Daily Mail.

Microplastics have been found everywhere you can imagine. From fish and frogs to mice and mosquitoes, their bodies have been found, on average, to contain 40 pieces of microplastic, reported Daily Mail. As the top of the food chain, humans are exposed to microplastics, too. “We live on a ball inside a bubble,” microplastic researcher Steve Allen at University of Strathclyde, Scotland, told Wired. “There are no borders, there are no edges. It (plastic rain) raining on the land and then getting blown back up into the air again, to move somewhere else. There’s no stopping it once it’s out.”

1. What does paragraph 3 mainly talk about?

A．How microplastics should be handled.	B．How microplastics are used widely.
C．How microplastics pollute water.	D．How microplastics come into being.

2. What do we know about microplastics?

A．They are light and can be easily dealt with.

B．They result in both acid rain and plastic rain.

C．They have a diameter of at least 5 millimeters.

D．They have nearly affected the whole food chain.

3. What do Steve Allen’s words mean in the last paragraph?

A．No place is safe from microplastic pollution.

B．The atmosphere possesses the capacity to self-cleanse.

C．Countries should work together to fight plastic pollution.

D．It is important to remove microplastics somewhere else.

4. What’s the main purpose of the article?

A．To compare acid rain and plastic rain.

B．To warn people of the dangers of microplastics.

C．To call on people to reduce using plastic products.

D．To introduce the sources and effects of microplastics.

9 . Unusually bright light in the sky that appeared suddenly last June has got astronomers in great excitement. After months of study, they still aren’t sure what the object — universally referred to as the “Cow” — is. Whatever it is, says astronomer Liliana Rivera Sandoval of Texas Tech University in Lubbock, “It’s super strange.”

The Cow first appeared in telescope observations on 16 June 2018, in what turned out to be a small galaxy (星系) about 200 million light years away. “When we saw that we thought, let’s get on this,” says Daniel Perley, an astronomer at Liverpool John Moores University.

The early observations confirmed the Cow was truly strange. It didn’t show the obvious changes in its light output that an exploding star would make. Sandoval says as soon as she and colleagues knew the Cow was truly distant, they requested time on NASA’s Neil Gehrels Swift Observatory to see what the Cow was doing in X-rays. Although the X-ray brightness varied over the early weeks, “the spectrum (光谱) didn’t change, which is very unusual,” she notes. After 3 weeks, the X-ray signal began to vary more wildly while also dropping off   in brightness.

Many astronomers agree that the long and steady duration of the event means that it was powered after an initial explosion by some form of central engine. But what that engine may be is also far from clear. Some argue that it could be a very unusual star whose central part has collapsed (坍塌) inward after it exploded. Others say it is a tidal disruption event — a star being torn apart by a black hole. But that usually requires the supermassive black hole in the center of a galaxy, and the Cow is situated in its galaxy’s arm. So, some say, it could be a tidal disruption event generated by an intermediate mass black hole, although evidence for the existence of such smaller black holes remains controversial. “All explanations have problems,” Sandoval says, “I hope there are more Cows.”

1. What is astronomers’ main concern about the Cow?

A．What it is.	B．How it forms.
C．When it appears.	D．Where it is from.

2. What did Sandoval and her team hope to find out about the Cow in X-rays at NASA?

A．What the Cow was doing.

B．How far the Cow is from the earth.

C．Whether the Cow is an exploding star.

D．Why the X-ray signals varied wildly.

3. What do Sandoval’s words at the end of the text probably mean?

A．The research results help little.

B．More Cows will appear.

C．Extra attention should be paid to the Cow.

D．More information is needed.

4. What is the best title for the text?

A．A Strange Explosion in Deep Space

B．An Interesting Observation of NASA

C．A Wide Range of Changes in the Galaxies

D．A Great Achievement in Astronomy

10 . Japanese officials say they are pleased with the quality of the asteroid (小行星) material collected by a spacecraft and returned to Earth.

Last week, officials from Japan described the samples (样品), which were collected from the Ryugu asteroid in July 2019. Ryugu sits more than 300 million kilometers from Earth. Japan’s unpiloted Hayabusa2 spacecraft removed the material after making a hole into the asteroid.

The space agency said the July 2019 mission (任务) aimed to collect samples from below the surface of Ryugu. During an earlier operation in February 2019, Hayabusa2 collected material from a different part of the asteroid. The second collection effort resulted in sample pieces as big as 1 centimeter. The black material looked similar to charcoal and was very hard. It did not break apart when picked up or poured into another container.

Earlier this month, space officials described the samples Hayabusa2 removed on its first mission as smaller, sandy pieces. They were collected from the surface of Ryugu. Hayabusa2 was launched in December 2014 and arived near Ryugu in June 2018. The Japanese space mission aims to use the samples to learn more about how our solar system formed.

To get the second set of samples in July, Hayabusa2 used an impactor to knock the asteroid’s surface. The aim was to collect material unaffected by space radiation or other environmental conditions. The size differences suggest different hardness of the bedrock of the asteroid. One possibility is that the place of the second touchdown was a hard bedrock and larger particles broke and entered the container.

Hayabusa2 is now on another mission to a smaller asteroid, called 1998KY26. The Japanese government expects the aircraft to take 11 years to reach that asteroid. Hayabusa2’s new mission aims to study possible ways to prevent large meteorites (陨石) from hitting Earth.

1. What are these asteroid materials used to do?

A．Study how the solar system was born.	B．Determine the movement of asteroids.
C．Study the environment on the asteroid.	D．Uncover when the asteroid was formed.

2. What is the Japanese spacecraft’s next mission?

A．To discover new planets.	B．To fetch more materials in space.
C．To travel around the solar system.	D．To explore ways to protect the earth.

3. What can be learnt about the two samples?

A．They were collected in the same place.	B．They both were black and hard.
C．They came in different shapes.	D．They were of equal weight.

4. Which of the following can be the best title for the text?

A．Japan Makes Progress in Studying Solar System

B．Japan Is Pleased with Latest Asteroid Samples

C．The Secret of an Asteroid Comes to Light

D．The Earth Faces Threats from Space