1 . Coral reefs are some of the most diverse and valuable ecosystems on Earth. Coral reefs support more species per unit area than any other marine (海洋的) environment, including about 4,000 species of fish, 800 species of hard corals and hundreds of other species. Scientists estimate that there may be millions of undiscovered species living in and around reefs. This biodiversity is considered the key to finding new medicines for the 21st century. Many drugs are now being developed from coral reef animals and plants as possible cures for cancer, viruses, and other diseases.

Healthy coral reefs support fisheries as well as jobs and businesses through tourism and recreation. About half of all managed fisheries depend on coral reefs and related habitats for a part of their life cycles. The National Marine Fisheries Service estimates the commercial value of U. S. fisheries from coral reefs is over $ 100 million, Local economies receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef ecosystems.

Coral reef structures also buffer (缓冲) shorelines against 97 percent of the energy from waves, storms, and floods, helping to prevent loss of life, and property damage. When reefs are damaged or destroyed, the absence of this natural barrier can increase the damage to coastal communities from normal wave action and violent storms. Several million people live in U. S. coastal areas near coral reefs. Some coastal development is required to provide necessary infrastructure (基础设施) for coastal residents and the growing coastal tourism industry.

Despite their great economic and recreational value, coral reefs are severely threatened by pollution, disease, and habitat destruction. Once coral reefs are damaged, they are less able to support the many creatures that live on them and the communities near them. When a coral reef supports fewer fish, plants, and animals, it also loses value as a tourist destination.

The Xi’an City Wall is the most complete city wall that has survived China’s long history. It     1     (build) originally to protect the city     2     the Tang dynasty and has now been completely restored (修复). It is possible       3     (walk) or bike the entire 14 kilometers.

We accessed the wall through the South Gate. The wall is 12 meters high and from here you can see streams of people moving inside and outside the City Wall.

After     4     (spend) some time looking at all the defensive equipment at the wall, we decided it was time for some action and what     5     (good) than to ride on a piece of history!

We     6     (hire) our bikes from the rental place at the South Gate. My bike was old and shaky     7     did the job. It took us about 3 hours to go all     8     way around the Xi’an City Wall. Supposedly you can do it in two hours, but we stopped at the different gates and     9     (watchtower) to take pictures or just to watch the local people going about their     10     (day) routines.

The iceberg that was for a time the biggest in the world is no more. A68, as it was known, covered an area of nearly 6,000 km²    1    it broke away from Antarctica in 2017. That's like a small country. But satellites show the mega-berg has now virtually gone, broken into countless small fragments    2    the US National Ice Center says are no longer worth tracking. Most glaciologists regard A68 as the product of a very    3    （nature）process, and it has nothing to do with human-induced climate change.

6 . City's icons celebrate milestones

Happy birthday to these big apple attractions

150TH

The Met isn^’t the only New York City institution celebrating an anniversary in 2020 - 2021.

130TH

April 2021 marks the 130th year of Carnegie Hall, the prestigious landmark that has delighted audiences with performers from around the world, including Frank Sinatra, the Beatles and Gustav Mahler.

125TH

Another NYC mainstay with a recent anniversary is the New York Public Library. Established in 1895, the main branch in midtown Manhattan, with its entrance famously flanked by lion statues named Patience and Fortitude, is a must-visit landmark that turned 125 in May 2020.

90TH

Almost a hundred years ago, competing skyscrapers shot into the atmosphere in a race to become the world's tallest building. At 1 ,046 feet, the Chrysler Building — which celebrated its 90th anniversary in May 2020 - was the first to hold the title, but only briefly.

90 TH

One year after the Chrysler Building was built, the Empire State Building was completed, topping off at 1,250 feet (or 1,454 if you count the antennae and spire) and remained the world's tallest building for a respectable 40 years. The iconic skyscraper — synonymous with the Big Apple itself — turns 90 in May 2021.

Many buildings along the Yangtze River have been destroyed during the flood season,     1     the Guanyin Pavilion (亭子) in the middle of the river has continued to stand tall even after more than 700 years. How does this ancient pavilion make     2    ? Described as “the first pavilion on the Yangtze River”, the Guanyin Pavilion     3     (build) in the Song Dynasty and then rebuilt in the Yuan Dynasty. Today, the pavilion     4     (sit) on a piece of dragon-shaped rock in the middle of the Yangtze River. Located outside the city of Ezhou, Hubei Province, the pavilion was constructed on a huge rock about 30 meters from the bank of the river.     5     (face) west, the pavilion is 24 meters long, 10 meters wide and 14 meters in     6     (high) . The base is made with a one-meter- high stone pile. The entire base is     7     (beautiful) combined with the rock, and the whole building is shaped     8     a boat in the direction of the flowing water. More importantly, a very strong stone wall was set up     9     (protect) the main body from the floods. The ancient pavilion is still standing more than 700 years later,     10     shows the wisdom of ancient Chinese people.

8 . “It has nothing in common with anything else on the Bund(外滩) "said Ben Wood, the American architect behind Shanghai's famous Xintiandi District, commenting on the Fosun Foundationafter its completion in 2016. "The great thing about the Bund is that it'sgrand. Perhaps a building that can stand out is needed here to show that acompany is progressive. But it's not grand.”

For now, however, the FosunFoundation ---a new theatre ---is proving popular with riverside tourists.

Located in the Bund FinanceCenter, the theatre was designed by co-operation of two world-known Britishdesign firms: Foster+ Partners and Heatherwick Studio. The architecturalhighlight is the outward appearance ---a golden, three-layered(层) steel bamboo curtain that hangs fromthe third floor. But what makes the architecture really unique is that it"dances" : repeatedly each day, the curtain slowly moves ---opens andcloses--- with music. This visual element, combining East and West, looks likeboth an ancient Chinese crown and a Western harp (竖琴). The building's ground floor entrancelooks unclear, but once inside, you'll see the space reveal a hall and cafe, and traditional Chinese theatres on the upper floors. Although there're onlyfour stories above ground, the building houses several music halls on its threeunderground floors.

“The opportunity to makesomething new in this culturally historic location was extraordinary, "said Thomas Heatherwick, Heatherwick Studio founder. "We tried to make itan interesting addition to show Shanghais mix of modern and historicarchitecture.”

The Fosun Foundation is only part of a bigger plan for this economicand cultural center in China. Along the Huangpu River, a massive waterfront artarea is being built. Shanghai hopes to play a larger role in the global artindustry in the coming years.

What Shanghai makes of thisnew riverside project remains to be seen. But with the Fosun Foundation open tothe public, the area's rapid transformation is bringing up discussions inChina's arts scene and beyond.

The highest point on Earth has a     1    (new) announced height. Mount Everest is 29,031. 69 feet above sea level, according to survey results presented today. That is more than two feet higher     2    the altitude previously recognized by the government of Nepal.

The height,     3     was announced on December 8 in a joint     4    (state) by the Survey Department of Nepal and Chinese authorities, is the result of a multiyear project to measure the mountain. As the first serious survey of Everest in 16 years, the effort has been closely followed by the geographic community—particularly scientists analyzing how a devastating 7. 8 magnitude earthquake in 2015     5    (affect) the region.

Last spring a small group of Nepalese surveyors and guides experienced the     6    （bite) wind of a nighttime climbing, reaching the top at 3 a. m. local time.

“We long     7    (deliver) the message that we can do something with our own resources and     8    (technique) manpower,” Khimlal Gautam, chief survey officer for the project, told National Geographic last year.

In 1856, mathematician Radhanath Sickdhar found that Everest was the     9     (high) mountain in the world while he was working for the Great Trigonometrical Survey, a project devoted to surveying and mapping the Indian subcontinent. Since then, a handful     10     surveys have sought to pin down the mountain's true height with the best technology available at the time.

10 . In the South Atlantic Ocean, there is an island called Tristan da Cunha, which is a six day boat ride from the nearest town Cape Town in South Africa. There’s no airport on Tristan. Every month or so, a boat will bring visitors but not many. The boat will also bring mail and supplies. You can only see about 270 people, 300 cows, 500 sheep, and a whole lot of penguins there.

The British tried to build a military base there in 1816. They gave up after a year. But a soldier and his family talked a few people into staying. Those people slowly built a community. Few trees grow on the island. So they found wood that washed ashore. They used it to build homes and boats. For food, they raised cows, sheep and pigs. They fished and planted potatoes. They promised to share everything they had. Sometimes ships brought supplies to Tristan. But for many years, no one there used money. Instead, people on the island traded potatoes for supplies. It cost five potatoes to send a piece of mail.

Today, nearly everyone on Tristan is a farmer. The island’s main industry is fishing. It has a single factory that cans fish.

Several times, bad luck has nearly destroyed the town on Tristan. In 1885, men died in a boat accident. That left 13 women and only 4 adult men on the island. Still, everyone stayed. In 1961, a bigger disaster stuck. The town was destroyed by a volcanic eruption. All 290 people on the island moved to England. But soon, nearly all of them moved back to the island and rebuilt their town.

What’s so special about life on this lonely island? For islanders like Harold Green, that’s an easy question to answer. Green has lived on Tristan his whole life. He left when the volcano erupted. But England was too loud and too crowded for him. He came back because the island is peaceful.