Detian Waterfall crosses from China to Vietnam, and joins the Ban Gioc Waterfall on the Vietnamese side. Shared by both China and Vietnam, it     1     (regard) as the largest transnational waterfall in Asia and the fourth largest transnational waterfall in the world with over 200 meters in width and over 60 meters in vertical (垂直的)     2     (high).

This three-tier (层) waterfall is surrounded by picturesque karst peaks, sometimes a dream-like mist, and so on adding     3     its magnificence and making it one of the most scenic waterfalls. So it is also very photogenic and sure to attract all visitors.

The     4     (good) time to visit Detian Waterfall is summer     5     it gets more spectacular and awe-inspiring with more clear water flow and     6     (extreme) green surrounding.

During the visit, you can ride a bamboo raft     7     (enjoy) its grandness from an even closer distance. Besides, you can take     8     walking path to get right up to the main waterfall, and climb alongside part of the waterfall to reach up to the top of the waterfall to admire an open view of the waterfall and beautiful karst mountains in the background.     9     (get) up close to the waterfall, you may feel the spray from it to help reduce the heat. Detian Waterfall is an off-the -beaten-path destination and a very     10     (please) getaway from the busy and noisy city life.

6 . Burning coal for energy adds planet-warming carbon dioxide(CO2) to Earth's atmosphere. As the planet heats up, experts warn that simply cutting greenhouse gas emissions（排放） will not be enough to avoid global warming. CO2 must also be remcved from the atmosphere.

Existing experimental machines that pull CO2 directly from the air are too expensive to be widely used. But a new effective technology to remove CO₂ already exists. It is not expensive and easy. It is forests. Planting trees and watching forests are effective ways to clean the air.

Forests used to cover large areas of the Appalachian Mountains in the eastern United States. In the state of West Virginia, coal mining left the land there bare, without trees. Over the years, coal mining and cutting forests took over 90 percent of the red spruce（云杉） forests.

Chris Barton works for the University of Kentucky. He started a group called Green Forests Work, aiming to put trees back on the roughly 400 , 000 hectares of land.

However, Barton explains the land has problems. "If you planted trees on these places, they just didn't grow. The ground was too hard. Water didn't infiltrate（渗透）. The trees can't root. Oxygen can't circulate in those environments. "Using heavy equipment, workers tear the ground. In this way, the trees put down roots.

Barton says not everyone believes the solution is a good idea. "We've had a lot of doubtful look at us twice from people. But after we do it, there's no question that it was the right thing to do. "And it has worked. Forests are coming back to the grounds.

Scientists say that, in West Virginia alone, restoring red spruce forests to the area could send what is equal to 56 million barrels（桶）of oil into the ground. But it will take time—a long time. Around the world, experts say, nature offers powerful tools to fight climate change. But patience is needed. Nature works, but slowly, in its own time.

The world's oldest known wild bird is a 70-year-old albatross (信天翁)    1     （name）Wisdom. Since last fall, she and her mate     2     (sit)on an egg. Last month, their chick hatched (孵化).

The Midway Atoll (环礁)     3     (make) up of two small islands in the Pacific Ocean.     4     area is home to about 3 million seabirds. About 1.3 million of these birds are Laysan albatrosses, like Wisdom Albatrosses are huge birds-their wings measure around 2 meters.

In 1956, when Wisdom was about five, she was banded by a scientist, Chandler Robbins. In 2002, when Mr. Robbins returned to Midway, he was     5     (excite) to find Wisdom again and realized she was over fifty.

Albatrosses normally have just one partner. But Wisdom has lived so long     6     she has had several partners. Akeakamai has been her partner since around 2012. It takes so much effort to hatch an egg     7     raise a chick that many albatrosses only lay one egg every other year.

Wisdom laid her most recent egg in late November of last year. Since then, she and Akeakamai had taken     8    (turn) sitting on the egg and keeping it warm. The chick arrived on February 2.

Now Wisdom and Akeakamai are keeping busy,     9    (take) long trips over the sea to gather food for their chick. These trips can last for days and can cover as much as 1,600 kilometers. Scientists think Wisdom's age and experience are     10     (possible) helping keep her safe on these trips.

8 . Humans take first place when it comes to making long-term changes to the earth, but we aren’t the only species to make a mark with infrastructure(基础设施）．A new look at an 1868 map has shown that beaver dams (河狸坝）in Michigan have been holding strong for at least 150 years.

The map is the work of Lewis Henry Morgan, who first traveled to Michigan in the late 1850s for his railroad work and started studying the beavers in what is now the city of Ishpeming. The resulting book, 1868’s The American Beaver and His Works, had a map that included 64 beaver dams and their ponds (池塘）．It was Carol Johnston of South Dakota State University who realized the value in Morgan’s map to modern ecologists (生态学家）. She created an updated version using air photos and compared the two, discovering that about 72 percent of the dams and ponds still exist.

While not all of the dams are still in active use, the findings show the unusual engineering abilities of the North American beaver. The fact that so many structures are still standing after all this time is truly impressive; they are even older than many of humankind’s most beloved structures, including the Eiffel Tower. “The findings prove that beaver works have been changing the North American landscape for centuries,” Johnston says.

For more, check out Morgan’s work in full on the Internet Archive, which includes lovely passages like this one, “As the dam is not a necessity to the beaver, his normal living place being rather natural ponds and rivers, and holes in their banks, it is an amazing fact that he should have voluntarily worked himself, by means of dams and ponds of his own construction, from a natural to an artificial way of life.”

On that note, don’t forget that International Beaver Day is April 7. These guys deserve some serious praise.

9 . Sometimes the simplest solution is the best one. That seems to be the case when it comes to the issue of wind turbines (涡轮机）killing birds.

According to a study conducted at a wind farm on the Norwegian archipelago of Smøla, changing the color of a single blade(叶片）on a turbine from white to black resulted in a 70-percent drop in the number of bird deaths.

In the past few years there has been a huge increase in global wind power, with more than 60 GW of new generating capacity(发电量）added worldwide in 2019. If the turbines are placed correctly, wind power is cheaper, cleaner and more sustainable(可持续的). Not to mention that a turbine farm is easier on the eye than a huge power plant.

But these farms aren’t good for everybody - especially not for local bat and bird populations. The US Fish and Wildlife Service calculated that nearly 300,000 birds were killed by wind turbines in 2015, which is a lot fewer than those that die as a result of hitting electrical power lines each year. Yet it still remains an environmental issue, even as bird deaths from turbines seem to be going down as the industry moves to larger turbine blades that move more slowly.

Studies have suggested that birds may not be skillful at noticing obstructions to their flight path, and adding different colored fan blades can increase birds’ chances of spotting a rapidly turning fan.

At the Smøla wind farm, regular checks of four particular wind turbines found the four turbines killed 18 birds that flew into the blades over six years. In 2013, on each of the turbines in the test group, a single blade was painted black. Over the next three years, only six birds were found dead due to hitting the wind turbines.

Researchers said the results are a step in the right direction toward better, more sustainable treatment of our flying friends.