1 . After years of heated debate, gray wolves were reintroduced to Yellowstone National Park. Fourteen wolves were caught in Canada and transported to the park. By last year, the Yellowstone wolf population had grown to more than 170 wolves.

Gray wolves once were seen here and there in the Yellowstone area and much of the continental United States, but they were gradually displaced by human development. By the 1920s, wolves had practically disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around.

The disappearance of the wolves had many unexpected results. Deer and elk populations — major food sources (来源) for the wolf — grew rapidly. These animals consumed large amounts of vegetation (植被), which reduced plant diversity in the park. In the absence of wolves, coyote populations also grew quickly. The coyotes killed a large percentage of the park’s red foxes, and completely drove away the park’s beavers.

As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many farmers opposed the plan because they feared that wolves would kill their farm animals or pets.

The government spent nearly 30 years coming up with a plan to reintroduce the wolvers. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. Elk, deer, and coyote populations are down, while beavers and red foxes have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.

4 . Over the last two days, much of Spain has been coated with dust (灰尘) , and the skies have turned bright orange. A huge cloud of dust from the Sahara Desert is causing the strange weather. The dust cloud is expected to spread to other parts of Europe.

Across much of Spain on Tuesday morning, a thin layer (层) of red dust coated everything outside. From streets to sidewalks to balconies, everything was covered with a layer of dust. As the sun rose, the dust in the air turned the skies in some cities a strange orange. The cause of the dust and unusual sky colour wasn’t a forest fire, but dust from the Sahara Desert.

Every year, a large cloud of dust rises from the Sahara Desert. It’s called the Saharan Air Layer. Usually, it crosses the Atlantic Ocean as part of a natural cycle that helps develop farmland and beaches in Central and South America.

But sometimes, depending on the weather, the layer of dust gets forced to the north. Large sandstorms in northern Africa lift sand and dust into the air, where it gets blown towards Spain. Though the particles (微粒) in the air come from sand, they’re much more like dust than sand at a beach.

These kinds of storms aren’t unknown in Spain. In fact, it has a special name. It’s called a “calima”. This calima is so large that it can be seen from space. A NASA scientist who studies weather in the atmosphere says it’s like a river of dust in the air. That river of dust has met with a river of wet air driven by strong winds.

Spain’s weather service described the dust storm as being “very intense (强烈) ”. At one point on Tuesday, the air quality in Madrid was the worst in the world. Government health experts warned people not to go outside without a mask, and to keep their windows and doors closed at home.

It’s     1     little hard to believe that Iceland has experienced 18,000 earthquakes in a week. Most of them have been too small to feel. The seismic (地震的) activity suggests that a volcano in the southwest of Iceland,     2     hasn’t been active for over 800 years, may be about     3     (erupt). Iceland is a volcanic island and is used to the occasional earthquake. However, quakes have unsettled     4     (resident) in the capital city Reykjavik. Scientists say despite the large number     5     quakes, there has been very little damage.

Iceland     6     (lie) on top of the meeting of tectonic plates. Tectonic plates are pieces of Earth’s crust (地壳) around 100km thick on which Earth’s landmass sits. The plates below Iceland are     7     (constant) pushing North America and Eurasia away from each other at an extremely slow rate. Living on a tectonic plate means earthquakes can’t     8     (avoid). One Reykjavik resident spoke about his anxiety     9     (cause) by the 18,000 recent quakes. He said, “It is very     10     (usual) to feel the Earth shake 24 hours a day for a whole week. It makes you feel very small and powerless against nature.”

6 . This summer we witnessed interview teams at the North Pole wearing short sleeve shirts due to the warm weather. A study published on Aug 29 revealed more concerning issues in the supposedly coldest area of the world. Zombie ice from a massive Greenland ice sheet was confirmed to be melting, which would eventually raise global sea levels by at least 10 inches (27 centimeters) on its own, reported Associated Press (AP).

Zombie ice is the kind of ice that is still attached to thicker areas of ice, but is no longer getting fed by larger glaciers. Since glaciers are getting less snow to make up for the amount of ice melted, once the zombie ice is melted, it cannot be re-formed.

Scientists decided to look at the balance of the ice. In perfect equilibrium (平衡),snow in the mountains of Greenland flows down and thickens the sides of glaciers, balancing out what’s melting on the edges, according to AP. But in the last few decades, there is less refill and more melting, creating an imbalance.

Study co-author William Colgan at the Geological Survey of Denmark and Greenland told AP that 3. 3 percent of Greenland’s total ice volume will melt eventually. “Starving would be a good phrase” for what’s happening to the ice, Colgan added.

With a great number of natural resources buried under the earth, areas of melted ice revealed treasures that attracted the world’s richest men. According to CNN, in early August, there was a “treasure hunt” in Greenland. Billionaires, including Bill Gates and others, financially backed KoBold Metals, a US-based mineral exploration company, to explore the rare metals under the glaciers in Greenland. The company told CNN that since there were enough minerals to power hundreds of millions of electric vehicles, the critical resource is capable of powering the green energy transition (过渡).

While investors are taking advantage of global warming, experts express their concerns that the mineral exploration is likely to worsen the local environment, running out of the world’s resources at a faster rate.

7 . In the spring and summer months, thunderstorms are common.     1     In thunderstorms, lightning can strike people and buildings and is very dangerous.

It was reported that a man was struck by lightning when he was making a phone call under a tree. He died at once. You may not know it, but nearly 1,800 thunderstorms are happening at any moment around the world.     2     So what should you do during a lightning storm? Scientists say that a person’s chances of   being struck by lightning are 1 in 600,000.     3    

If you are indoors during a thunderstorm:

*Stay away from anything that is metal because lightning can come into the house through it.

*Don’t stand near the windows.

*Don’t take a shower or bath. Lightning can travel through water.

* Never use the phone.       4    

If you are caught in a thunderstorm outdoors:

*     5     If there’s no building around, try to find a low place to stay in.

*Do not go under a tree because the lightning could hit the tree and travel through the tree to hit you.

* Never use a cell phone.

Whales have been facing serious danger for a long time.

First, due     1     the greenhouse effect, glaciers are melting, and some living creatures in the Antarctic and the Arctic are in danger of     2     (extinct). Besides, with global warming becoming worse, life in other parts of the ocean has also been     3     (constant) affected, including whales.

Secondly, whaling activity is another killer. Historically, whaling has been popular in some overseas countries, such as England, Japan and Norway.     4     (regard) whales as a money-making machine is the reason why some people’s whaling can’t     5     (stop) easily. A kilogram of whale meat can fetch about $100 in Japan. Besides, advanced technology has increased the efficiency of whaling,     6     greatly reduced the number of whales. What’s more, some countries are still on whaling in     7     name of science.

The fact that whales have become endangered animals is alarming us. Some     8     (organization) have realized the importance of saving them and have begun working hard to do something for them. The international community     9     (make) a strategy against commercial whaling. In my opinion, governments should also make laws     10     (protect) whales.