1 . At ancient sites across the Amazon River basin, mysterious plots of unusually rich soil dot (点缀) the landscape. Scientists have long debated the origin of this “dark earth”, which is darker in color than surrounding soils and richer in carbon. Some people think this dark earth formed naturally, but the latest research has shown that modern Kuikuro people in Brazil create similar soil around their villages on purpose, which adds evidence to the idea that long-ago Amazons deliberately made such soil too. Perron, an earth scientist at MIT, reviewed interviews of Kuikuro people conducted by a Kuikuro filmmaker in 2018 and found that Kuikuro villagers actively make dark earth by using ash, food bits and controlled burns. “When you plant in hilly land, the soil is weak,” explained elder Kanu Kuikuro in one of the interviews. That is why we throw the ash, manioc peelings and manioc pulp. When comparing soil samples from ancient and modern sites, researchers found “striking similarities” — both were far less acidic than surrounding soils and contained higher levels of plant-friendly nutrients.

Analyses also revealed that dark earth holds twice the amount of carbon as surrounding soils on average. Scans (扫描) of the Xingu region suggest that the area is dotted with dark earth, and that hold as much as about 9 million tons of carbon — the annual carbon emissions of a small, industrialized country. “This number could roughly equal the annual carbon emissions of the United States when all dark earth across the Amazon is taken into consideration,” Perron says.

Figuring out the true value of carbon stored in the Amazon’s dark earth will require more data. Still, the research has significant influences on the Amazon’s future. The technique highlights how ancient people were able to live in the Amazon by developing sustainable farming that doubled as a carbon-storing technique. With more and more greenhouse gases entering the atmosphere, it could also provide a blueprint for developing methods of sustainably locking atmospheric carbon in the soil, helping fight climate change.

1. What can we infer from the dark earth across the Amazon River basin?

A．They are more acidic than surrounding soils.

B．They contain more organic nutrients.

C．They formed naturally.

D．They contain less carbon.

2. Why does the author mention the annual carbon emissions of the US?

A．To explain the difficulty of protecting dark earth.

B．To show the wide distribution of dark earth in Amazon.

C．To stress the huge carbon-storing capability of dark earth.

D．To reveal the large carbon emissions of the United States.

3. What does the author stress in the last paragraph?

A．The importance of developing sustainable farming.

B．The advanced farming technology in ancient tomes.

C．A possible solution to climate change.

D．A way of green agriculture.

4. Which is the best title of the text?

A．Urgency of Sustainable Development	B．Facts About the Dark Earth
C．Advantages of the Dark Earth	D．Wisdom of Ancient Amazons

2 . The grass swung gently above a crack in the limestone (石灰岩) and Ludvik Husu realized he had found what he was searching for: a new cave in Slovenia’s dramatic Karst (喀斯特) region.

The cave enthusiast, with more than 50 years of experience, told AFP that “the conditions were perfect ... all the signs pointed to something beneath” as he felt the air current push up from below.

The 63-year-old had come across a new, 60-meter-deep limestone cave, a discovery that made the headlines this summer in a country that prides itself on its 14,000 underground caves.

The tiny Alpine nation is unusually rich in caves, which are a major tourist attraction. Perhaps the best known is the Postojna cave system, the longest in Europe, discovered by another amateur enthusiast two centuries ago. It extends for 24 kilometers and has offered up valuable finds for biologists.

Stanislav Glazar, a Postojna cave guide, told AFP that more than 150 species have been discovered in the system.

Glazar said Postojna is one of the richest caves in the world “in limestone formations.” The cave, located about 50 kilometers south of the capital Ljubljana, was also home to the world’s first cave tourist train, which began transporting visitors in 1872.

Elsewhere in the Karst region, the cave systems are of historical, cultural and even extraterrestrial interest. For instance, the UNESCO-listed Skocjan system was where the European Space Agency sent some astronauts to prepare for life in space.

“Astronauts know that the Karst world is exceptional, in a similar way to the environment in space: you don’t know what to expect at your next step,” said Skocjan Caves director Tomaz Zorman.

But for Husu, it’s the exploration that proves most rewarding. Once he knows there is something beneath, he digs around the crack to widen it and alerts fellow cavers to help gain access. He then uses ropes and a lamp to go down to what are vertical entrances in most caves. But doesn’t he feel scared to enter such unexplored depths?

“You enter a cave out of curiosity — there is no fear! Those who feel fear should stay home,” he said.

1. What was people’s attitude towards Ludvik Husu’s new finding this summer?

A．Critical.

B．Positive.

C．Doubtful.

D．Indifferent.

2. What can be learned about the Postojna cave system from Stanislav Glazar’s words?

A．It has little biological value.

B．It has diverse limestone formations.

C．It is the most famous cave system in Europe.

D．It has been open to the public for two centuries.

3. What does the underlined word “extraterrestrial” in the seventh paragraph probably mean?

A．Financial.

B．Political.

C．Alien.

D．Biological.

4. What can be inferred from the text?

A．Slovenia is known for its Karst landforms.

B．Ludvik Husu started exploring caves before he was 13.

C．Slovenia has the most underground caves in the world.

D．Ludvik Husu is often upset about entering unexplored caves.

3 . If you have lived in New York City for many years, like I have, the skyline becomes part of you and your daily life.

When I was invited to visit the recently completed Summit One Vanderbilt, New York’s fourth-highest tower, I wasn’t expecting much. I felt like I’d seen it all and I thought that this observation deck (观测台) would be another space for a view of the city, but nothing else.

Let me tell you something: I have never seen one like this before. It sits on top of a building on 42nd street and Vanderbilt, right next to Grand Central Station. Once you have ascended to the top floor, you step into air, which makes you feel like being at l,000 feet above ground level with its mirrored floors. Once you make your way throughout the space, you feel like New York is part of a body, and your sense of space is challenged by the reflections of the light. The reflections create endless possibilities for photos and videos, and the light changes throughout the day. I took out my camera and began to take photos, feeling a connection with the city that no other observatory has been able to give me.

Summit is something unique, an art work with architecture. It will be an observatory that will change with the city. I personally can’t wait to take photos at sunset, or when winter arrives.

1. How did the author feel when invited to visit Summit One Vanderbilt?

A．Curious.

B．Happy.

C．Amazed.

D．Uninterested.

2. What does the underlined word “ascended” in Paragraph 3 probably mean?

A．Risen.

B．Turned.

C．Referred.

D．Adapted.

3. What can be learned about Summit One Vanderbilt?

A．It is the only tower in New York.

B．It lies far from Grand Central Station.

C．It provides a good place for taking photos.

D．It is exactly 1, 000 feet high from the ground.

4. What’s the purpose of the text?

A．To stress a point.

B．To introduce a site.

C．To raise awareness.

D．To promote tourism.

4 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式

Xi'an,or Chang'an as it was called for many centuries,has been a built-up urban area for over 3,000 years,and once     1    （serve）as capital for 13 dynasties.It is home     2     many immovable cultural heritages,three of     3     are on the UNESCO 's world cultural heritage list.

These days,the city has made     4    （effect）exploration in building modernity while preserving historical legacy（遗产）.A recent piece of news     5    （announce）by Shaanxi's cultural relic authority caused nationwide attention,that a ruin of ancient capital dating back to Qin Dynasty was unearthed during the construction of the Xi 'an MetroLine5.In order to protect the ruin,the metro line may have to change     6    （it）route.

    7     （face）the heavy and important task of protecting cultural relics while promoting urban construction,Xi’an made active    8    （attempt）.Rails of the metro system are built 15 to 20 meters underground in order to protect the ancient tombs which are     9     （usual）buried in the layer within5meters from the surface level.Besides,the metro constructors have also painted the walls inside the stations with historical stories,presenting       10     visual feast for citizens.

5 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

    1    (lie) under waters across the globe are an estimated three million shipwrecks, all of     2     indicate human attempts over the centuries to explore Earth's furthest corners. While there is little land on our planet left unexplored, the vast sea bed almost     3    (remain) unknown.

Considering our limited knowledge, it's not surprising that exploration of the oceans constantly brings about discoveries in various     4    (science) fields.

First, many archaeological finds are made in shallow waters, including whole cities     5    (bury) underwater. The ruins offer precious information about the past. However, the challenges of pressure, darkness and intense cold at vast depths make     6     difficult to discover more of the past.

Amazing biological discoveries are also being made, like the barreleye living 6,000 meters below the ocean's surface. Such discoveries enable us     7    (have) a better knowledge of the capacity for life even in extreme circumstances.

Additionally, so far more new natural resources such as fire ice     8    (find) in oceans. Besides, the research conducted by China's underwater vessels helps scientists identify areas for deep-sea drilling and better understand how the sea bed was formed.

Humankind is entering a new age of oceanic discovery. Oceans will be as familiar     9     us as the land where we live through all-round international     10    (cooperate).