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.

3 . 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.

Many people have realized that the whole world is being influenced by the change of the weather-making different places    1    (hot) than before. We    2    (experience) record-breaking high temperatures for more than a month so far. We are talking about temperatures above 40℃, which has a risk to life from heatstroke (中暑). We should pay attention    3    such a bad change to weather patterns.

With the whole world’s weather change likely to become more common in the future, we need to find    4    much better way to deal with possible unexpected events. Let’s start with    5    everyone can do to live in overheated places. We should all learn to walk on the shady part of the street. We’d better wear loose-fitting clothes made of cotton. At home, we need to keep the curtains, blinds or shutters (百叶窗)    6    (close). In this way, we can avoid    7    (have) sunlight warm the place    8    (direct). Of course, drinking enough cool water is also necessary during hot conditions. Larger social changes are also useful. People can choose to start    9    (they) work fairly early in the morning before the worst of the day’s heat really kicks in. Offices and shops can often close over these extra-hot    10    (hour). That is good for dealing with special high temperatures.

5 . 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.

6 . 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.”

8 . 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.