1 . In Shark Bay, Australia, bottlenose dolphins that aren’t related have been observed teaching each other a new way to use a tool, a behavior that until now scientists have found only in humans and other great apes. It’s also the first known example of dolphins passing on such knowledge within the same generation, rather than between generations. That’s significant, the authors say, because such social learning between peers is rare in nature.

In a practice called shelling, dolphins will chase fish into abandoned giant snail shells on the seafloor, then bring the shells to the surface and shake them with their noses, draining the water and catching the fish that fall out. In 2007, Krutzen launched a study of Shark Bay’s dolphins, identifying more than a thousand individual dolphins over 11 years. During this time, scientists observed shelling 42 times among 19 dolphins. Half of these events occurred after a marine heatwave in 2011, which may have caused a die-off among giant sea snails, leading to more abandoned shells on the seafloor.

Because of the length of their study, scientists had thorough knowledge of the individual dolphins, family histories, ages sexes, and behavior, making it easier for them to study the 19 dolphins that practiced shelling. For instance, they observed that the dolphins that practice shelling hang out with other shelling hunters, so it’s likely that they copy the action from those they spend time with, says study lead author Sonja Wild, a postdoctoral researcher at the University of Konstanz in Germany. Although 42 observations are a small data set, the scientists add it’s likely the behavior is actually common; it only lasts a few seconds, making it harder for people to spot it from a boat.

The team had assumed that environmental factors — specifically, whether shelling dolphins did so simply because they lived in a shell-rich area — could explain this peer-to-peer transmission (传递). A genetic trait (遗传特性) among a family group was another possible reason.

So the researchers combined their data on the dolphin sightings, as well as genetic and environmental data, into a computer model that proposed various ways shelling could be passed on between dolphins. The model that supported this kind of transmission was the strongest outcome, according to the study.

2 . Rolling electric power blackouts afflicted(困扰) roughly 2 million California residents in August, 2020 as a heat wave gripped(影响) the Golden State. At the center of the problem is a state policy requiring that33 percent of California’s electricity come from renewable sources such as solar and wind power, rising to a goal of 60 percent by 2030. Yet data showed that power demand peaks just before the sun begins to go down, when overheated people turn up their air conditioning in the late afternoon. Meanwhile, the power output from California’s wind farms in August was erratic.

California electricity grid operators warned that power shortages might become increasingly common when heat waves hit in the coming years. California still has some natural gas power plants that can be ramped up to(提高) supply energy when renewable supplies fail. “But some folks in the environmental community want to shut down all the gas plants,” Jan Smutny-Jones, CEO of the Independent Energy Producers Association, a trade association representing solar, wind, geothermal, and gas power plants, said in August, 2020. “That would be a disaster. 60 percent of the power in the California Independent System Operator electricity network was being produced by those gas plants in this summer. They are your insurance policy to get through heat waves.”

Union of Concerned Scientists analyst Mark Specht, by contrast, said that “The solution is definitely not more natural gas plants. Really, if anything, this is an indication that California should speed up its investments in clean energy and energy storage.”

4 . Harry Smith has a dog, Sarah Jane. They are best friends and love to take walks together. One day when they _________ in a park, the two of them _________a beautiful lake. Although Harry used a wheelchair, this usually wasn't a problem for him. _________ when his wheels got stuck that day, he quickly found himself thrown into the _________

As the 81-year-old, not being able to _________, screamed(尖叫)for help, Sarah jumped into action-she barked(吠叫)as _________ as possible. Luckily, the dog’s bark caught two men’s attention and they made their way over. One of the men, Edward Suhling, _________ in the water. And they got _________ from a police officer who just happened to be nearby. Together, the three of them _________ Harry out of the water as quickly as possible.

“I am __________ to Sarah and the three passers-by that helped __________ my life!” Harry wrote on the Internet. “And the __________ remains true-a man's best __________ is his dog.” Needless to say, Harry made sure to __________ his best friend of seven years how grateful he was in a way that every __________ loves: with food.

8 . The following properties which the World Heritage Committee has decided to include on the List of World Heritage are in danger according to Article 11 (4) of the Convention (公约).

Virunga National Park (Democratic Republic of the Congo)

Virunga National Park, covering an area of 790,000 ha., includes an outstanding diversity of habitats, ranging from swamps and steppes (沼泽和平原) to the snowfields. Mountain gorillas are also found in the park.

Cultural Landscape and Archaeological Remains of the Bamiyan Valley (Afghanistan)

The cultural landscape and archaeological remains of the Bamiyan Valley stand for the artistic and religious developments which from the 1st to the 13th centuries characterized ancient Bakhtria. The area contains a number of Buddhist monastic ensembles (佛教寺院), as well as strong buildings from the Islamic period.

Okapi Wildlife Reserve (Democratic Republic of the Congo)

The Okapi Wildlife Reserve occupies about one-fifth of the Ituri forest in the northeast of the Democratic Republic of the Congo. The reserve contains threatened species of primates and birds surviving in the wild. It also has some amazing scenery, including waterfalls on the Ituri and Epulu rivers. The reserve is inhabited by traditional nomadic pygmy Mbuti and Efe hunters.

Historic Center of Vienna (Austria)

Vienna developed from early Celtic and Roman settlements into a Medieval and Baroque city, the capital of the Austro-Hungarian Empire. It played an important role as a leading European music center, from the great age of Viennese Classicism through the early part of the 20th century.

9 . Depths of our Earth hold great wonders. Below we explore four deepest places on Earth.

Its entrance is located 2,285 meters above sea level. In 2018, scientists reached its bottom at 2,212 meters down. They squeezed through tiny openings to get from one cave to another. Rockfalls and floods waited secretly at every turn. Scientists could develop new medicines from microorganisms found in cave samples. Caves also record ancient life and past climates.

The Mariana Trench, with the maximum depth of 11,034 meters, is the deepest part of Earth’s surface. Pressure there is intolerable, but creatures like sea cucumbers (海参) still exist. Scientists exploring it can gain deeper insights into how plates move and why earthquakes and volcanoes occur.

The Dead Sea is the lowest point on land at about 1,400 feet (about 400 meters) below sea level. It’s nearly ten times saltier than ocean water, so you literally can’t sink in the Dead Sea! Scientists think it could go dry in a few decades. Despite its name, the Dead Sea holds life. A few kinds of algae (藻类) and bacteria love its salty water.

At the depth of 1,642 meters, Lake Baikal is the deepest inland body of water. The Baikal seal is the only known seal that lives in this world’s deepest freshwater lake. Scientists study the lake not only for the solid stuff beneath it that records climate history but because it’s in a zone where a plate is splitting apart, causing earthquakes.

Located in southwest China’s Sichuan Province, the Jiuzhai Valley runs more than 50 kilometers, towards the Sichuan Basin. The Jiuzhai Valley got     1    (it) name because there are nine Tibetan villages in the valley. It consists of three main valleys,    2    form a “Y” in shape. The clear mountain lakes, splendid waterfalls, colorful forests and the local ,Tibetan, ethnic culture all make it a unique tourist    3    (attract).

More than 400 million years ago, the region was    4    ideal breeding ground for various, prehistoric lifeforms. However, with the time    5    (pass), many lifeforms died off. Now the region is home    6    nationally protected animal species and 74 endangered plants. Historically, the ancestors of the Jiuzhai Valley    7    (be) from the remote Ngari region in Tibet. Today, the local people still maintain their Tibetan religious and folk customs.

In 1978, the Jiuzhai Valley    8    (name) as the Jiuzhai Valley Nature Reserve, becoming the first nature reserve     9    (protect)landscape and natural scenery in China.

Now a network of wooden walkways has been built to provide a     10    ( powerful) protection to the natural environment than before.