Though once secluded (与世隔绝的), even inaccessible, Kazakhstan today welcomes intrepid travelers with open arms.

Kazakhstan is the world’s largest landlocked (内陆的) country, and the     1     (nine) largest in the world. The country is one of the most economically advanced in Central Asia, thanks to     2     (it) abundant oil reserves and other valuable minerals.

Even for some     3     (experience) travelers, Kazakhstan is still     4     unfamiliar state. While home to the raw beauty of the steppe (草原) and mountain scenery, there are no yurts (蒙古包) like in Kyrgyzstan     5     Mongolia. The country also has a fascinating history of medieval (中世纪的) Islamic architecture.

But for those     6     have stepped foot in the country, its most     7     (attract) features are its unique landscapes and freedom.

Panfilov Park in the eastern-center of Almaty has plenty     8     places of interest that offer a whistle-stop tour of the city’s history. Not far behind the     9     (large) of them is the yellow, green and red Tsaristera Ascension Cathedral (大教堂), a visually attractive structure that is claimed to be one of the tallest wooden     10     (build) in the world.

On the north bank of Fuxian Lake in Chengjiang County, Yunnan Province sits a straw-hat-shaped mountain     1     (call) Maotian Mountain,     2     a 512-hectare site is praised as a “world-class treasure trove of fossils” by the international scientific community. On July 1,1984, young paleontologists in China discovered a fossil of the arthropod (节肢动物化石) with a long tail in Maotian Mountain. “    3     we had studied in China were just shell of fossils. The arthropods, lifelike fossils with legs, which belonged to fossils of soft-bodied animals, are     4     game changer in the research of China’s paleontology (古生物学)”, Hou Xianguang, a paleontologist said.

Scientists have obtained a large number of research results on Chengjiang Fossil Site. The reason why Chengjiang fauna (动物群) is     5     great significance is that it is closely related to the emergence of the animal tree of life.

Up to now, more than 20 phyla and more than 280 species     6     (record)in the Chengjiang Fossil Site, of which, 80% are new species. On July 1, 2012, the Chengjiang Fossil Site     7     (be) inscribed on the World Heritage List by UNESCO,     8     (become) China’ s first World Heritage Site for paleontological fossils.

The UNESCO evaluation says the Chengjiang Fossil Site is one of the     9     (early) records of a complex marine ecosystem of the early Cambrian communities. The property displays excellent quality of fossil     10     (preserve). It presents an exceptional record of the rapid diversification of life on Earth during the early Cambrian period.

3 . The Great Barrier Reef in Queensland has suffered several mass bleaching events due to the impacts of climate change. The Australian government turned down a proposal for a new open-cut coal mine near the Great Barrier Reef, considering environmental laws and the risk of “irreversible damage”. It was the first time the government had used its powers under environmental laws to reject a mine.

In turning down the project, Tanya Plibersek, the minister for the environment and water, cited significant potential environmental dangers to the reef, which is already heavily threatened by climate change.” The risk of pollution is real and the damage to the reef, once done, will never be repaired. “The project would have had unacceptable impacts on freshwater in the area and potentially on fragile seagrass meadows,” Plibersek said in a video posted on social media. She said that during the public consultation period, her department had received 9,000 public comments about the mine in just 10 business days.

The government has been under pressure from UNESCO to better protect the reef and in 2022, it pledged one billion Australian dollars for efforts to protect the fragile ecosystem, including climate adaptation measures and water quality programs. Last year, the Great Barrier Reef, which stretches for more than 2,300 kilometers, experienced its sixth mass bleaching event, due to warming waters caused by climate change.

The government, elected in 2022, came to power promising stronger action on the climate in a country still heavily depending on fossil fuels. But its climate policies are rated “insufficient” by Climate Action Tracker, which found Australia is not on course to meet targets to limit warming to 1. 5 degrees Celsius above pre-industrial levels. The government has rejected calls from the country’s Green Party to turn down all new fossil fuel projects.

5 . The black cloud rising every day at sunset in the Chihuahuan Desert went largely ignored for thousands of years. Native Americans noticed it, but did not track its source. Cowboys thought the cloud was smoke pouring from the earth, and avoided it.

In June of 1901, however, a teenage cowboy named Jim White happened to see the large, black cloud. He was curious and went to investigate. Instead of finding a volcano, as he had imagined, he discovered something equally amazing. It was a big mass of bats. Two days later, he returned with a lantern to explore further. It took him so long that his lantern went out. He managed to refill it with just enough oil to find his way back to the entrance.

The next time Jim White went to the cave, he brought a friend and supplies. They explored for three days and returned with descriptions that were so fantastic that few people believed them. The cowboys on nearby farms and the people in the tiny town of Carlsbad treated Jim’s stories as tall tales and nothing more.

After years of exploring the caves and finding no one to believe his stories, Jim White decided to create his own tourist attraction. He established trails (路线) along the paths he had found. One day in 1915, two men asked Jim for a tour. After seeing the caves, the men returned with a professional photographer named Ray V. Davis. Local doubts were finally put to rest by the photographs of the hidden beauty that Jim had discovered. All 13 locals of Carlsbad finally took a tour of the caves, which came to be known as Carlsbad Caverns.

In 1923, the government sent an official named Robert Holly to tour the caves. Later that year, the caves were stated a national monument (古迹), and in 1930 they became a national park. Jim White lived to see the Carlsbad Caverns become world-famous. Today, tourists can hike to and tour some of the 100 known caves in this huge natural wonder, thanks to the cowboy from New Mexico.

6 . Humans are responsible for 25% to 40% more of the total share of methane emissions(甲烷排放)than previously estimated, according to a new study in Nature.

Methane is one of the most powerful and effective greenhouse gases: about 28 times more effective than carbon dioxide at trapping heat in the atmosphere. It's responsible for about a quarter of global warming. It's produced naturally by animals, volcanoes, and wetlands, but it's also a byproduct of oil and gas production. It's this last form of methane that the study focused on.

Researchers used ice core measurements from Greenland from 1750 to 2013, plus previous data from Antarctica. They melted the ice to let the small quantities of ancient air trapped inside come out. These act a bit like time capsules,allowing us to learn about the methane in the atmosphere at the time. They used carbon-14, which comes from living things, as a substitute(替代物)to determine whether the methane they found came from biological sources. Until 1870, around the time when we started using fossil(化石)fuels, almost all methane came from these sources. After that, there was a rise in methane that didn't have any carbon-14, from ancient fossil sources in which carbon-14 had disappeared. That allowed the researchers to compare natural methane with methane caused by human activity.

If more methane is created by humans, there's an even bigger opportunity to control how much we release. Methane stays in the atmosphere for only a decade(compared with 200 years for carbon dioxide). So efforts to cut methane, which mostly comes from the production and transportation of gas and oil, could bring great benefit right away.

Every day we use energy. We use it for cooking, for heating and for lighting our cities. The energy comes from many different     1     (source). It can come from the sun, wind and water, but the energy we depend on the most comes from deep inside the Earth. These include coal, oil, and natural gas.

These fuels come from the remains of plants and animals. It takes millions of years     2     (make) them. However, with the world’s population     3    (grow), more and more of these fuels are dug up from the ground. Yet these fuels are non-renewable. When they     4    (use) up, they will be gone forever.

We need to have a strong sense of     5    (responsible) and it’s high time for us to think about     6     we can help save energy and preserve these fuels.

What about turning off anything     7     (electricity) we are not using? That’s a start! We can also recycle things such as newspapers, cans, bottles, and plastic—including plastic bags. Plastic bags start out as either oil     8     coal, and one big city can use millions of plastic bags in a year. When we use recycled things, it takes less energy     9     making something new.

Cars consume a lot of fuel, but there     10     (be) a variety of measures that car owners can take to preserve fuel. Try asking your family whether we can take a bus or walk instead of using the car.

8 . 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.