1 . Ho Khanh is a middle-aged farmer, living in a village on the edge of Phong Nha-Ke Bang National Park in Vietnam. What is special about him is that he has discovered Son Doong, the largest cave in the world.

"I first found the cave about thirty years ago, in 1991," he says. "I was out collecting firewood near the national park. My family were very poor, so I decided to go deeper into the forest to find some aloe, which is very valuable. Not many people went that far into the forest because they were afraid of the wild animals."

Soon Khanh lost his way. "I sat down with my back to a huge round rock," he says. "Then I heard the sound of a strong wind and running water coming from behind me." He found the entrance to a huge cave, with a wide river coming out of it. Khanh thought he was walking into a great cave. With no ropes or lights, he did not go further into it.

Khanh's story spread like wildfire, but not everyone believed him. "I wanted to prove that I was telling the truth, but I couldn't remember the way to the cave." Then one morning early in the winter of 2006, a group of cavers from Britain came to ask Khanh for help, as they had heard about his discovery fifteen years before.

Khanh agreed to help the team to find the cave, but after three days in the jungle, they lost their way. "I just couldn't remember where it was," he says. The team came back twice, but each time they were beaten by the thick jungle. Finally the cavers left.

In 2009, Khanh headed to the jungle one cold winter's morning. "I stopped by a big round rock," he says. "There was the same strong wind, the sound of water running—I knew I'd found the cave at long last. "Soon the British cavers returned and followed Khanh on a six-hour trip deep into the jungle. On April 14 they found Son Doong.

2 . One girl is being praised for a letter of apology she wrote to the rangers (园林管理员) at the National Parks Service (NPS). She reportedly _________ a rock home. In expressing her _________, the girl also returned the rock to the park. Later the NPS shared the letter on their Facebook page.

“Dear Park Ranger, I _________ like Tom Branch Falls,” the girl, named Karina, began her letter. “I love it so much that I _________ to take a souvenir home.”

“So I took a rock. I’m _________, and I want to return it,” she said. The heartfelt letter _________ with a postscript (附言) of “also look at the back”—where the girl _________ a picture of Tom Branch Falls. _________ for Karina, the park rangers were _________ by her sincere apology and even __________ back.

“Dear Karina, thank you for returning the rock! It has made its way back to Tom Branch Falls. If every __________ took a rock home, that would __________ 11 million rocks would be gone from the park every year,” the park officials wrote in their Facebook post.

“Now that you know to leave __________ the way you find it, we hope you will help share this __________ with others,” the officials wrote. “It is always a __________ thing to give others the chance to discover something meaningful!”

4 . The Great Barrier Reef's outlook remains “very poor” despite coral (珊瑚) recovery over the past year, Australian government scientists said Monday, just days before a UNESCO ruling on the site's world heritage (遗产) status.

The United Nations cultural agency recommended last month that the world's largest reef (珊瑚礁) system be placed on its endangered list because of damage to the corals largely caused by climate change.

The Australian Institute of Marine Science (AIMS) said the corals were now in a “recovery window” after a decade of harmful heat stress and cyclones (旋风). But such opportunities were becoming rarer due to the influence of climate change, the government agency, which has monitored the reef for 35 years, said in its annual report released today. “The increasing emergence of climate-related extreme weather events and starfish outbreaks is causing more severe and frequent pressures, giving the reef fewer opportunities like this to recover,”CEO Paul Hardisty said. The scientists surveyed 127 reef sites in 2021 and found hard coral cover had increased at 69 of the 81 locations surveyed in the past two years.

Separate scientific research released last October found the 2, 300-kilometre (1, 400 miles) system had lost half its corals since 1995, with a series of ocean heatwaves causing mass coral death.

Britta Schaffelke, research program director at AIMS, said the latest findings provided a slight hope that the reef still has the power of recovering. But she added that its future is still very poor because of the dangers of climate change and other factors that are affecting the reef.

UNESCO has urged Australia to take urgent climate action but the government has long resisted calls to commit to net zero emissions (排放) by 2050. The government has said it hopes to meet the target “as soon as possible” without harming its economy, insisting dealing with climate change requires a global effort. The reef was worth about US $4. 8 billion a year in tourism for the Australian economy and there are fears that an “in danger” listing could weaken its tourist appeal.

5 . Scientists from the University of Texas at Austin have finally solved the mystery of a huge fossil(化石）that has been unlabeled and unidentified sitting at a Chilean museum for almost a decade. The relic which looks like a flat football, is the largest known soft-shelled egg from a marine reptile（海生爬行动物）that lived on the earth over 66 million years ago. Measuring more than 11 by 7 inches» it is also the second-largest egg belonging to any known animal, only behind the now-extinct elephant bird.

The rare fossil named " The Thing" was discovered inside a rock formation in Seymour Island off the coast of Antarctica in 2011 by a team of researchers including David Rubilar-Rogers. Over the years, the paleontologist（古生物学者）at Chile's National Museum of Natural History has showed the strange fossil to every geologist that came to the museum. However, no one was able to identify “The Thing's" origin until Julia Clarke» a professor at UT-Austin's Jackson School of Geosciences, visited in 2018.

“I showed it to her, and, after a few minutes, Julia told me it could be an egg!" Rubilar-Rogers said.

To confirm Clarke's suspect, Lucas Legendre, a student at UT-Austin who led the study, examined the fossil under a microscope. Sure enough, he found several layers of membrane（薄膜），confirming that the fossil was indeed a soft-shelled egg, similar to the obvious, quick-hatching eggs laid by some modern-day snakes. “The shell is very thin,” said Clarke.

The fossil's identification led to an even bigger mystery—what animal could have laid an egg this size? After considering several potential parents, the researchers concluded that the egg was laid by an ancient marine reptile like a masseur（沧龙）. The fact that the rock formation where the egg had been found had fossil evidence of baby masseurs and the offspring of other marine animals further strengthened their theory.

The Honghe Hani Rice Terraces(梯田), in southern Yunnan, China, cover a huge 16, 603-hectare area. The terraces,     1    (know)to all of the world now, were made out of a thick forest by the Hani people. The terraces rise at different angles from a shallow 15°    2     a steep 75°, forming a wonderful landscape(景观)that     3    (be)rare in the world.

In 2003, the terraced fields were     4    (official)recognized by UNESCO as a World Cultural and Natural Heritage site. About 1,300 years ago, the Hani people first     5    (come)to the steep mountains. They struggled against the difficult terrain(地形), successfully creating the terraces, where they grew rice in order to make     6    (they) living. Over the past 1,300 years, the Hani people have developed a complex system of channels     7    (bring)water from the forested mountaintops. They show great appreciation for natural phenomena such as rivers, mountains, the sun, fire     8     the moon. They have also created a complete farming system     9     involves cattle, ducks, and fish and supports the     10    (produce)of red rice, the area's main crop.

The landscape changes through the year. In April the terraces are all green as rice starts to grow; in later parts of the year it is yellowish brown as the rice ripens. In February, the terraces become bare earth, with the water reflecting(反射)the sky.

8 . One billion people in the world are short of water. How can this problem be solved. Some suggestions have been to desalinate ocean water or to build enormous water pipelines from areas where water is abundant. (Suggestions such as these prove extremely expensive when they are actually used.) One possibility that scientists are considering is pulling icebergs from either the North Pole or the South Pole to parts of the world with a water shortage. Although many questions must be answered before such a project could be tried, moving icebergs seems a reasonable possibility in the future.

Engineers, mathematicians, and glaciologists from a dozen countries have been considering the iceberg as a future source of water. Saudi Arabia is particularly interested in this project because it has a great water shortage. Scientists estimate that it would take 128 days to transport a large iceberg (about 1/2 square mile) to Saudi Arabia. Yet the iceberg would be completely melted by the 104th day. Therefore, insulation would be essential, but how to insulate the iceberg remains an unsolved problem.

The problems in transporting an iceberg are numerous. The first problem is choosing the iceberg to pull. The icebergs that form in the North Pole are quite difficult to handle because of their shape. Only a small portion extends above the water — most of the iceberg is below the surface, which would make it difficult to pull. South Pole icebergs, on the other hand, are flat and float like table tops. Thus they would be much easier to move.

How can a 200-million-ton iceberg be moved. No ship is strong enough to pull such enormous weight through the water. Perhaps several ships could be used. Attaching ropes to an iceberg this size is also an enormous problem. Engineers think that large nails or long metal rods could be driven into the ice. What would happen if the iceberg splits into several pieces during the pulling. Even if an iceberg with very few cracks were chosen, how could it be pulled through stormy waters. Furthermore, once the iceberg reached its destination, very few ports would be deep enough to store it.

All of these problems must be solved before icebergs can become a reasonable source of water. Yet scientists estimate that it will be possible to transport them in the near future. Each year, enough icebergs form to supply the whole world with fresh water for a full year. In addition, icebergs are free and nonpolluting. As a solution to the world’s water problems, icebergs may be a workable possibility.

9 . The Great Wall of China has a long _________ of more than two thousand years. It walks from the east to the west in _________ China. It is about 6,000 kilometers _________ . We Chinese people _________it “Ten Thousand Li Great Wall”.

The Great Wall is about seven _________ high. In many places _________ is wide enough for ten men to walk side by side along the top. _________ can run along the top, too. Along the Great Wall there are tall and strong watchtowers (烽火台). People _________ the Great Wall with stones and bricks (砖块). There are big stones on _________ sides and on the top.

It is not easy to build such a great wall over the ______________ and down the valleys (山谷). When you look at the Great Wall, you will be ______________ at it. The Chinese people built it ______________ any machines. They did all the work with ______________ . They carried the earth in baskets and pulled the stones with ropes. They worked in wild places. So it was ______________ to give them enough clothes to wear. Thousands of people died of the hard work and hunger.

Every year thousands and thousands of people come to ______________ the Great Wall from all over the world. It is a monument to the great Chinese people.