More than a fifth of all reptile species (爬行动物) are threatened with extinction, which could have    1     destructive impact on the planet, a new study warns. Fifty-two experts analysed data from the Global Reptile Assessment, which, in the past 17 years,     2     (receive) contributions from more than 900 scientists across six continents.

Although many reptiles live in dry    3     (environment) such as deserts and scrubland, most species occur in forests,     4     they suffer from threats such as logging and conversion of land for agriculture. Hunting is also a major threat to reptiles, especially turtles and crocodiles (鳄鱼), many of which are    5     risk of extinction. Another major factor that     6     (contribute) to forming the threat is the introduction of invasive (入侵的) species.

The study is not all depressing. Scientists noted that conservation efforts to help other animals are likely to be protecting reptile species as collateral (抵押品). “We found, surprisingly, that if you set out    7     (protect) places where birds, mammals (哺乳动物) and amphibians (两栖动物) under threat live together, you’ll protect many more    8     (threaten) reptiles at the same time, ” said Bruce Young, co-leader of the study.

Yet reptiles also require direct,     9     (globe) efforts to protect them, said Cox. Governments will negotiate (议定) new targets to protect biodiversity,     10     (include) reptiles, in Kunming, China, later this year.

In the United States alone, there are more than 80 brands of bottled water. That makes the United State one of the top bottled-water-consuming nations. A single-serve water bottle offers great convenience, which isn’t the only reason for bottled water’s rise in popularity. Many people believe that bottled water is cleaner and more healthful than tap water from public water system.

That is a misconception. In the United States, tap water is regulated by the U.S. Environmental Protection Agency (EPA). By federal law, tap water is supposed to be tested every year to make sure it is safe to drink. Tap water also often contains naturally present minerals, such as calcium and magnesium. Those minerals make tap water healthful.

The impact of bottled water on the environment is staggering. Approximately 2.7 million tons of plastic are turned into disposable bottles each year. The manufacturing of all those bottles requires large quantities of crude oil and water. That process produces greenhouse gases. Bottled water is often shipped long distances to reach consumers, sometimes across vast continents. The transportation of the product uses even more fossil fuels and creates more pollution.

“Back to the tap” movements are cropping up around the world. They encourage people to use tap water and reusable “sports” bottles rather than bottled water. Colleges and universities have begun to ban the use and sale of bottled water on their campuses. San Francisco, Concord (Massachusetts), and other cities across the United States have adopted bans on single-serve water bottles. Cities in Canada (Toronto), Australia (New South Wales), and several states in India have taken similar action. Many bottled water companies are trying to do their part. They have reduced the amount of plastic in their bottles and bottle caps. Bottled water has become an international phenomenon, and it can be an important source of safe drinking water. We should not lose sight of a more environmentally friendly source, however: the water that comes out of our taps.

Hua Weiguang,     1     retired teacher from Tongliao, Inner Mongolia Autonomous Region, is a photography enthusiast.

A decade ago, the arrival of tree planters     2     (catch) Hua’s attention and the photos of the tree planters     3     (take) by Hua are evidence of the     4     (remark) transformation of the land. In those photos, hats, scarves and goggles, for the workers fighting desertification, are basic necessities to protect them     5     the wind and sand. There was no way to avoid the brutal summer heat in the land so the workers had to lie down on the ground or curl up in the narrow shade of their cars to cool off. And they also had to eat their lunch amid the blowing sands, taking in the small pieces of sand with their food.

“    6     we don’t fool the tree, it won’t fool you. You take it     7     (serious), and then it behaves in the same way to you. You put efforts to make it live, and the tree lives up to your     8     (expect),” the planters say.

China’s forest resources have increased by over 70 million hectares in the past decade,     9     (rank) first in the world. One tree after another, a green Great Wall has been built. Brush by brush, a green field     10     (paint) over the yellow sandy land up to now.

6 . People have long known that dogs have a great sense of smell. But scientists weren’t sure whether stressed people had a special smell. And if they did, they weren’t sure whether dogs could detect that smell.

All day long, our bodies go through changes and produce different chemicals. They come out in our breath and sweat, slightly changing the way we smell. But it wasn’t known if stress could cause changes that could be detected. So researchers at Queen’s University Belfast, led by scientist Clara Wilson, collected breath and sweat samples(样品) from 36 different people. They got samples when the people were calm and when they were stressed.

The calm part was easy. They asked people to report their stress level, and measured their heart rates and blood pressure. The people were asked to wipe their skin with a clean piece of cloth. Then they had to put the cloth sample in a tube(管子), breathe on it hard three times, and seal the tube.

Then the scientists asked a really difficult math problem, and forced people to do it in their heads quickly. They kept telling the people to hurry up, and didn’t give them any help. That lasted for three minutes. Then the researchers collected two more sweat and breath samples. They also asked the people about their level of stress, and measured their heart rates and blood pressure. Most people said they felt very stressed. On average, the heart rate increased from about 91 beats per minute to about 105 beats per minute.

The scientists used one of the stressed samples, along with two clean pieces of cloth, to train the dogs to find the stressed smell. Then came the challenge: the dogs had three choices: a sample from a calm person, a stressed sample from that same person, and a clean piece of cloth. In all, the dogs did 720 of these tests. They correctly identified the stressed sample about 94% of the time.

The results make it clear that stress does have a smell that dogs can detect. Ms. Wilson says the news could be especially useful in training service dogs, since their job is to help relieve stress.

7 . 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.

8 . 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.”

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.