【推荐1】U.S. teens spend more than eight hours a day on screens, and there’s growing concern over how social media may affect their mental health. Now, a new study has found that limiting screen time to about one hour a day helped anxious teens feel better about their body image and their appearance.

The study arose from the personal experience of Helen Thai, a doctoral student in psychology at MeGill University. “What I noticed when I was engaging in social media was that I couldn’t help but compare myself,” Thai says. She was well aware that social media posts often feature polished, airbrushed or filtered images that can alter (改变) appearances in an unrealistic way, but it still affected her negatively.

So, Thai and a team of researchers decided to test whether cutting time on social media platforms including Instagram, TikTok and Snapchat would improve body image. They recruited a few hundred volunteers, all of whom had experienced symptoms of anxiety or depression, which could make them vulnerable to the effects of social media. Half of the participants were asked to reduce their social media to 60 minutes a day for three weeks while the other half continued to use social media with no restrictions, which averaged about three hours per day.

The researchers gave the participants surveys at the beginning and end of the study, which included statements such as “I’m pretty happy about the way I look,” and “I am satisfied with my weight.” Among the group that cut social media use, the overall score on appearance improved from 2.95 to 3.15 on a 5-point scale. This may seem like a small change, but any shift in such a short period of time is striking, the authors say.

“The study is encouraging, but it only included people who had symptoms of anxiety or depression. It’s worth evaluating this approach with other groups, such as people with or at risk of eating disorders. It’s also possible that the benefits of cutting back could extend more broadly to anyone in this age group,” says Psychologist Andrea Graham, co-director of the Center for Behavioral Intervention at Northwestern University.

1. What problem may social media bring to teenagers according to Thai?

A．They may become addicted to the Internet.

B．They tend to become sensitive to others’ comments.

C．They may have unrealistic expectations of their image.

D．They tend to compare themselves with the images posted online.

2. What can we learn about the participants during the study?

A．They scored their appearance twice.

B．Half of them stopped using social media.

C．They hoped to improve their body image.

D．Most of them showed dissatisfaction with their weight.

3. What did Graham think of the study?

A．It was a good try but had limitations.

B．It was well designed but poorly conducted.

C．It was a failure but the methods deserved praise.

D．It was encouraging but the evidence was unreliable.

4. Which of the following is the best title for the text?

A．Shorter Screen Time, Better Feelings on Look

B．How to Help Teenagers Limit Screen time

C．How Social Media Changes Teenagers

D．Less Anxiety, Better Image

【推荐2】Back in 2015 my colleague Adam Frank of the University of Rochester and I were having lunch near Columbia University's campus in New York City. As at Fermi's lunch 65 years earlier, the conversation was about the nature of spacefaring species. And inspired by Fermi's mental calculation, we were trying to craft an investigative strategy that made the fewest possible unsubstantiated assumptions and that could be somehow tested or constrained with real data. At the center of this exercise was the simple thought that waves of exploration or settlement could come and go across the galaxy, with humans happening to come into being in one of the lonely periods.

This idea relates to Hart's original fact: that there is no evidence here on Earth today of extraterrestrial（外星的）explorers. But it goes further by asking whether we can obtain meaningful limits on galactic（星系的）life by constraining the exact length of time over which Earth might have gone unvisited. Perhaps long, long ago extraterrestrial explorers came and went. A number of scientists have, over the years, discussed the possibility of looking for artifacts that might have been left behind after such visitations of our solar system. The necessary scope of a complete search is hard to predict, but the situation on Earth alone turns out to be a bit more manageable. In 2018 another of my colleagues, Gavin Schmidt of NASA's Goddard Institute for Space Studies, together with Adam Frank, produced a critical assessment of whether we could even tell if there had been an earlier industrial civilization on our planet.

As fantastic as it may seem, Schmidt and Frank argue—as do most planetary scientists—that it is actually very easy for time to erase essentially all signs of technological life on Earth. The only real evidence after a million or more years would boil down to isotopic or chemical stratigraphic anomalies—odd features such as synthetic molecules, plastics or radioactive fallout. Fossil remains and other paleontological markers are so rare that they might not tell us anything in this case.

Indeed, modern human urbanization covers only on order of about 1 percent of the planetary surface, providing a very small target area for any paleontologists（古生物学家）in the distant future. Schmidt and Frank also conclude that nobody has yet performed the necessary experiments to look exhaustively for such non-natural signatures on Earth. The bottom line is, if an industrial civilization on the scale of our own had existed a few million years ago, we might not know about it. That absolutely does not mean one existed; it indicates only that the possibility cannot be completely eliminated.

1. The word “unsubstantiated”（in paragraph 1）is closest in meaning to ________.

A．unconscious

B．unknown

C．unnatural

D．unsupported

2. What assumption was the author and his colleague's investigative strategy built on?

A．No other species have ever settled on Earth except human beings.

B．Extraterrestrial explorers come and go at increasingly short intervals.

C．No spacefaring species have visited the Earth since humans emerged.

D．Extraterrestrial explorers once built an industrial civilization on Earth.

3. It can be inferred from the passage that if we want to prove if there used to be an industrial civilization on Earth, we should________.

A．turn to isotopic or chemical stratigraphic anomalies

B．find as many signs of technological life as possible

C．unearth more fossil remains than we do now

D．leave behind synthetic things like plastics

4. According to the passage, what are Schmidt and Frank most likely to agree with?

A．Human urbanization should be expanded for the sake of research.

B．We cannot say for sure that no civilization existed before ours.

C．Non-natural signatures on Earth have been studied exhaustively.

D．An industrial civilization came into being a few million years ago.

【推荐3】Lacking a nose, insects such as butterflies and bees use their antennae (触须) to detect smells. Those smells help them find food and more. What happens, though, when air pollution beats the smells on which these creatures depend? Those insects become less likely to visit a flower. That’s the finding of a new study.

People depend on insects to help the plants to make many of the fruits, nuts and vegetables we eat. Past studies showed urban air pollution might hide the smells insects use to find flowers. For instance, ozone(臭氧), an ingredient in smog, can break down the smells from flowers. Computer models predicted this would cause problems for insects seeking flowers for a meal. But scientists weren’t sure that would happen in real life.

James Ryalls and his team decided to find out if it would. Ryalls is a biologist at the University of Reading in England. Working in a field of black mustard plants, his group created a system made up of rings eight meters in diameter. Each area was open, so nearby insects could fly into it. The researchers pumped pollutant gases into these rings: Two rings received diesel fumes(柴油废气). Two more got ozone. Another two got both gases. A final pair of rings was a control and received no added gases.

The tests took place over two summers. During each field season, the scientists counted how many times insects visited the flowers in each ring. “The results were much more severe than we thought,” Ryalls says. Adding both the diesel fumes and ozone pollution “caused up to 90 percent less insects to be able to find the flowers that they need for food,” he says. This was in comparison to the pollutant-free rings. This surprised the scientists and made them worried about the food resources of humans.

1. What is the finding of the new study?

A．Insects have noses.	B．Insects can feel smells.
C．Smells are helpful for insects to get food.	D．Polluted air makes insects hard to find food.

2. What does the underlined word “ingredient” in Paragraph 2 refer to?

A．Part.

B．Shape.

C．Flower.

D．Colour.

3. What can we know about the tests?

A．Seven rings had gasses.	B．They lasted two summers.
C．They were led by a biologist.	D．They were done on the playground.

4. What can be a suitable title for the text?

A．Save Flowers.	B．Poor Insects.
C．Tests by Researchers.	D．Environment and Food.