1 . In a bustling city in Arizona stood a high school where most of the students live in poverty. Among them were four sons of Mexican immigrants, Juan, Oscar, Luis, and Alfredo. These boys, coming from ________ backgrounds, often found themselves overlooked and underestimated. Bonded by fate and friendship, they shared a common passion for ________. Two science teachers there decided to enter their high school into a complicated ________ robotics competition sponsored by the NASA and the Naval Research. Excited for the news, these four boys signed up for the competition.

With enthusiasm and energy, they started calling mechanical engineers for design help. They were ________ that these kinds of robots require glass syntactic flotation foam, a type of floating material used in various marine applications.________ money, all they could afford was some PVC pipes and duct tape (强力胶布).________, they searched the city for various spare parts, gathering whatever they could to bring their vision to life. With the teachers’ guidance and encouragement, they ________ together a robot with no more than metal and wires.

As they worked on their robot, the boys also faced personal challenges. Juan struggled with the weight of family responsibilities; Oscar ________ a deep-seated fear of failure; Luis’s heart ached from the constant peers’ mockery (嘲笑) for his ________ accent, and Alfredo longed for acceptance and belonging.________ these obstacles, they persevered, leaning on each other for support and inspiration.

After a few test runs of their robot, they piled into a second-hand van to head to the competition. Upon entering the main pool area, they noticed the college teams wearing matching outfits, with robots sponsored by big companies. Feeling a bit nervous, the boys put the robot in the water for a test run.________, the PVC didn’t hold up, causing the robot to leak and sink.

However, instead of letting this ________ ruin their spirits, the boys put their heads together and came up with a brilliant solution. 12 hours later, armed with 8 super-absorbent pads to plug the leak, the robot was ________ into the pool again. This time, their robot performed admirably. Gliding gracefully through the waters, it navigated the course with precision and speed,________ the judges and audience alike. This underwater robot, a symbol of their determination and ________, conquered the waters, defeated engineering powerhouse MIT and ranked first in the country. This was not just a win for those four but a victory for every underdog with a dream.

2 . Like anything built by evolution, the human body has many downsides, teeth without exception. Adult humans only get one set of teeth, which must last about 60 years. However, a(n) ________ of poverty, sugar-rich diets and poor hygiene means 2.5bn people globally suffer from tooth decay, in which acid produced by mouth-living bacteria eats away the hard enamel (牙釉质) that ________ the outside of a tooth, leading to further infection and damage. Once decay has set in, all a dentist can do is to fill the gap with artificial filling.

But in a paper published in Cell, Hannele Ruohola-Baker, a stem-cell biologist at the University of Washington, and her colleagues offer a possible ________. Stem cells have the ________ to turn themselves into any other type of cell in the body. It may soon be possible, the researchers claim, to use those ________ cells to regrow a tooth’s enamel naturally.

The first step was to work out how enamel is produced. As enamel-making cells, known as ameloblasts, disappear soon after a person’s adult teeth have finished growing, the researchers ________ samples of tissue from human foetuses (胚胎), which contain plenty of functioning ameloblasts. ________, they checked to see which genes were especially active in the enamel-producing cells. It turned out that genes designed to bind to calcium were particularly busy.

________ that information, Dr Ruohola-Baker and her colleagues next checked to see whether the stem cells could be persuaded to ________ ameloblasts. The team devised various drugs designed to activate the genes expressed in functioning ameloblasts. That worked, with the engineered ameloblasts producing the same proteins as the natural sort.

For now, the work is more concept than a medical treatment. The next step is to boost enamel production further, with a view to ________ beginning clinical trials. The hope is that, one day, medical versions of the team’s findings could be used as biological implants, to ________ a patient’s decayed teeth.

Stem-cell-based therapies are not the only ones heading to clinical trials. Another treatment, known as biomimetic repair, involves rebuilding the tooth crown using synthetic (人工合成的) proteins, which are similar, but not quite ________, to human enamel. The proteins could be included in toothpaste and even cough drops. But synthetic formulations can be less ________ than human enamel.

It will take time for either technology to become reality. One question is how durable the enamel made by stem-cell-derived ameloblasts is. Another is how best to deliver the stem cells to a patient’s mouth. But these findings are ________. As any dentist will tell you, prevention is better than cure. ________, a better cure would be always welcome. There is no doubt that this research offers a new prospect for future dental care.

3 . One summer midnight several years ago, standing outside a wooden cabin in Michigan River, I looked up. The sky was filled with thousands of stars, the sight of which was almost enough to make me, a non-believer, offer a word of ___________ up into the star-filled sky. But to whom? Perhaps to Johan Eklof, author of The Darkness Manifesto.

As a bat scientist, Eklof’s work on bats requires a specific kind of darkness—the ___________kind, unpolluted by light. But this category of darkness is ___________. In the 1980s, Eklof tells readers, two-thirds of the churches in Sweden’s southwest housed bat colonies. Not any longer. “Today, forty years later, research I’ve done with my colleagues shows that this number has been reduced by a third, ___________ light pollution and other factors. Because the churches are all ___________ like carnivals(嘉年华) in the night,” he writes. “We are surrounding ourselves with light.”

Excess light is incredibly ___________ to the complex eco-systems nocturnal (夜间活动的) animals inhabit. It ___________ away the bats that Eklof studies. It frightens light-sensitive moths, leaving them easily ___________ to predation(捕食) or flying endlessly into lights that will never return their love. Baby turtles crawl away from the shoreline toward the lights of distant coastal cities and reef fish eggs go unhatched. Birds do not migrate ___________ and even they forget to sing. Modern advancements such as LED lights could significantly reduce some of the worst impacts, but they have not. At least, not yet.

It is worth mentioning that middle-aged writer like Eklof can ____________ for a darker world — for darkened campuses and unlit parking lots. But darkness is not safe for everyone. We need to address the social issues that make lighted places so ____________ in the first place.

The bottom line: We can change if we want to. Some of the solutions to light pollution— motion-detecting lights, shielded lights that do not ____________ light upward, artificial light with wavelengths that is similar to natural light—are already within our grasp, if we just ____________ them. “We could just turn it all off, but I guess we don’t want to,” said Eklof in a recent interview. “____________, it’s vital we find a middle way.”

Right now it is hard to know what that middle way might look like. In 50 years, every city could be equipped with an array of programmed and ____________ low-impact LED lights. Or we might have completely forgotten what darkness is—the sky filled with little moons.

4 . China becomes a world leader in clean technology by fighting environmental pollution, sharing experience.

Erik Solheim, former executive director of the United Nations Environmental Programme, said he is __________ with China’s phenomenal achievements over the past decade in fighting environmental pollution and climate change, and in its march toward __________ development.

This is very __________ to his Twitter followers. Solheim’s latest tweets include one about China ranking first globally in planted forests and forest coverage growth, __________ a quarter of the world’s new forests in the past decade; one about China producing 60 percent of global solar energy last year and 80 percent of solar panels; and another highlighting the fact that 80 percent of the world’s new offshore wind capacity was installed in China last year.

He believes that it’s time for the rest of the world to __________.

For Solheim, who is also the former Norwegian Minister of the Environment and Minister of International Development, China’s achievements on the climate and environmental fronts all started with its fight against__________.

“People wanted to see beautiful skies over their cities,” he told China Daily. “The __________ fast reduction in air pollution in Chinese cities over the last decade shows how fast China can act. This has now spilled over into renewable energy, nature protection, electric mobility, tree planting and a lot more. Today, China is the world leader in all __________ technologies.”

The latest __________ from China’s Ministry of Ecology and Environment prove Solheim’s observations that the country is rapidly switching to a more sustainable path.

Minister of Ecology and Environment Huang Runqiu told a news conference on Sept 15 that the country’s toughest measures and greatest progress on the ecological and environmental front have occurred in the last decade.

He said that __________ painstaking efforts to combat pollution, clear waters and blue skies have become more commonplace.

While poor air quality used to be a source of frequent public complaints, the average __________ of hazardous airborne PM2.5 particles dropped from 46 to 30 micrograms per cubic (立方的) meter between 2015 and last year.

About 87.5 percent of days last year were rated as having good air quality, up 6.3 percentage points from 2015, making China the country with the biggest __________ in air quality in the world.

In the last decade, the __________ of water at or above Grade III in the country’s five-tier water quality system rose 23.3 percentage points to 84.9 percent, close to the levels in developed countries. Carbon intensity, or carbon emissions per unit of GDP, has declined by 34.4 percent, with coal __________ for 56 percent of total energy consumption, compared to 68.5 percent a decade ago.

China has has legislated or revised roughly 30 laws and regulations, some of which focused on water resource protection, including the Water Pollution Prevention and Control Law, which was modified in 2017, and the Yangtze River Protection Law, which __________ last year.

5 . Once just a science fiction idea, VR (Virtual Reality) has now become more accessible than ever. Wear a pair of VR glass which is connected to your computer and you can_______ a lot of things without stepping out of the room. From climbing the highest mountain in the world to flying a spacecraft, the things you can do with VR are _______.

This new ‘_______’ is becoming more and more popular China. The Report on Chinese VR Users’ Behavior was released on March 18. The report is _______ a survey of 5,626 people, aged between 15 and 39, from across the country. It shows that up to 68.5 percent of people have heard of or are _______ in VR products.

But surprisingly, it isn’t _______ technology that has made VR so popular. “VR has been around for many years, but it will stick this time because there’s enough computer power and the price will just keep _______,” Todd Richmond, a VR group member with the Institute of Electrical and Electronic Engineers in the US, told USA Today.

VR is expected to change various different fields. _______, VR could be used to treat patients with acrophobia (恐高症) by making them think they were standing on top of a high building, or train pilots and miners _______ they had to actually risk their lives in highly dangerous working environments.

“If you have perfect virtual reality, ________ you’ll be able to simulate everything that a human can imagine, it’s ________ to predict where you go from there,” Palmer Luckey, the inventor of the Oculus VR goggles, told NPR.

But the technology is still ________ perfect. Users report feeling motion sickness, headaches and other________while wearing VR glass. Also, ________ more and more tools are flooding the market, the software that runs VR games and simulators has yet to catch up with all the new advancements. It could take a while for VR to be ________ accepted.

When every new technology is first introduced, the technology itself is the driving force. But for it to really blend into people’s lives, meeting basic and practical needs should be the main aim.

6 . According to a survey conducted by wenjuan.com for the China Youth Daily, 71.0 percent of the 1,538 people polled said they watched short videos on a________basis. 61.8 percent believed that long-term viewing of short videos could interfere with their normal social interactions; and 65.2 percent suggested that video platforms step up in issuing regular________so that users could take a break.

This appeal for external aids to help________ the addictive habit hints at the crushing hold short videos have on the shiftless majority— many of them are not utterly ________ self-control in other circumstances.

Another recent survey of juveniles found 65.6 percent of them have watched short videos, and 20 percent of them just couldn’t stop watching.

For as you click on those seemingly________videos, your life will be thrown into a mindless spiral (螺旋)as we eagerly move from one piece to the next, each lasting 20 to 30 seconds, and are shocked, amused, and outraged in rapid________.

You never have a chance to get________, for you are always curious about what the next piece would be like,________more. All that is needed is a slight twitching (抽动) of one of your fingers.       

Respondents do believe some videos could be useful by teaching you how to cook， how to apply make-up, practice wellness, or buy things. There was even an alleged (声称但未经证实的) telecom fraudster publicizing his________and daring the police to catch him in Dubai, according to him.

It is shocking to realize that a published video itself would have ________ acquired a degree of authenticity and enough to prevent all intentions and the need for checking, even________ such basic facts as authorship.

So it is natural that 36.7 percent of the respondents in the wenjuan.com survey cited the issue of false and misleading content in short videos as an issue, and relevant authorities should have stepped in long ago to________it.

Yes, juvenile-only modes have been________for some time, but it is so easy for children to avoid this.________ , there is an equal need for a mechanism to prevent adults from becoming addicted, notably by limiting the lime they are allowed to view the videos. Thus, when 37.0 percent of the respondents said that, as far as viewing habits are concerned, parents should be a role model to prevent the imitation of juveniles. Maybe all parents should________their mobile phones for a moment of self-reflection.

7 . When it comes to anxiety over online data privacy, the first and most common legal solution comes to mind: more transparency. If firms are required to tell people what information they collect, and do so in a simple and obvious manner, people would be able to ___________ doing business with those that adopt abusive privacy practices.

There is one ___________ with the transparency solution. There is no evidence that it works! (And there are mountains of evidence that it fails.) Even when the information people are asked to share is highly private and ___________, and even if the notices about the ways firms collect, use and share this information are delivered in the simplest and most concise manner, people still don’t read the notices and don’t change their ___________. A recent experiment tried to deliver the privacy notices to users in the format of a simple “nutrition facts” box, to no avail. The notice still went ___________ and people shared the same amount of sensitive personal information as they do when the notices are long and cluttered.

If simple notices are not read or used by people, the hopes for ___________ choice flee. Users are not going to ___________ Google’s personalized ads or to personalize the Facebook’s privacy setting. These consumers might comparison-shop among services based on various quality and service measures, but not on the basis of ___________ features.

It is also important to dispel a second perceived solution to privacy ___________: lawsuits. There are numerous class action lawsuits percolating in courts, alleging violations by websites of privacy statutes. Google,____________, has long been defending against the complaints that its Gmail service, which scans the text of its users’ emails, is a violation of the Wiretap Act (窃听法). Many of these lawsuits eventually fail because they cannot prove a ____________ injury. But even the few that succeed are not going to change the behavior of firms. They will only teach firms to write more ____________ privacy notices and require more frequent clicks “I Agree” from users.

A third legal solution fueled by privacy anxiety is the “right to be forgotten”. It gives users the right to request search engines to ____________ links to personal information that are no longer accurate or relevant. Viewed by its ____________ as a major landmark in privacy protection, the right to be forgotten mandate is ultimately proving to be a storm in a tea cup. In one year, Google reported to have received only 218,000 requests (or which it granted about half). Only a minor number of users are ____________ sensitive to privacy issues to exercise the cherished right.

8 . The Lipstick Effect Absent During This Pandemic

With customers stuck inside their homes, they don’t seem to be________to wear or purchase lipstick and instead are stocking up on sheet masks and hand sanitizer (消毒液). This is a change from typical customer behavior, with lipstick sales________ experiencing a boom during economic crises.

In the four years from1929 to1933, industrial production in the United States halved whereas sales of cosmetics rose. A(n)________pattern emerged around the turn of this century. An executive at cosmetics giant Estee Lauder________a “lipstick index” after sales of expensive lipstick jumped following the 9/11 terror attacks. More________, sales of lipstick at John Lewis department stores in the United Kingdom rose 31 percent in the three months leading up to the end of June last year in the wake of Brexit.

________not everyone is counting on the lipstick effect to work this time around. With beauty retailer Mecca forced to close its 100 stores across Australia and New Zealand, owner Jo Horgan________that it’s still too early to tell whether this effect will lead to sales growth.

In the past few months, Ms.Horgan’s focus has been on Mecca’s online offerings in an attempt to ________a portion of last year’s $444 million turnover (营业额 ). She has launched a(n)________host experience of free and personalized beauty consultations via FaceTime for Mecca customers.

“My gut feeling is that while people are self-isolating at home, they will start trying to look for ways to________ themselves and really enrich their soul by focusing on their skin, body and hair treatments, ” she says.

A similar trend has been________in sales at online beauty retailer Adore Beauty, which has seen a considerable increase in new customers. This increase, however, has failed to________into lipstick sales. Founder Kate Morris said Adore Beauty had seen three times as many new customers as normal but that lipstick and lip gloss sales were down 24 percent.

“While everybody is talking about the lipstick effect, it is not what we are currently seeing.________we are seeing big jumps in anything hygiene related. People have got the________about washing their hands. We are selling triple the amount of hand wash and hand sanitizer than we were a month ago,” she said.

Adore Beauty turned over more than $100 million last year and employs a staff of 170. Ms. Morris is looking to hire an additional ten staff members to cope with the increased demand while also trying to fund the further________of her brand.

She said the online retailer has also recorded big jumps in “essential” categories, with moisturizer up 73 percent last month and hair treatments up 43 percent.

9 . The U.S. Department of Health and Human Services recommends that adults do at least 150 minutes of moderate to higher-intensity physical activity each week, and it should be in ________ of at least 10 minutes each for substantial health benefits, which has led many to ________ about the inefficacy of brief activities. Why people take two minutes going up the stairs if more than 10 minutes is ________ to make it worthwhile for health?

But now a study suggests something else: go ahead, take the stairs! Every minute ________ toward reaching the 150-minute goal, whether it’s part of a 10-minute period of activity or not. The purpose of the study conducted at the University of Utah was to see if moderate to vigorous physical activity in less than 10-minute episodes was ________ to weight outcomes. The study, published in the American Journal of Health Promotion, found that each minute spent ________ in some kind of moderate to vigorous physical activity — be it walking the dog, vacuuming, or taking the stairs — was associated with lower BMI and lower weight.

“The idea here is, you can do a minute at a time and that’s not a problem,” Jessie Fan, lead author of the new paper and a family and consumer studies professor at the University of Utah, told Today.

For the women who participated in the study, each minute spent in higher-intensity activity was associated with a 0.7 drop in body mass index (BMI). For a 5'4" woman, that means a ________ of nearly half a pound, which may not sound like much, but that’s just for one minute. Little by little, they add up.

The authors concluded that the current 10-minute ________ guideline was based on health benefits other than weight outcomes and that their findings showed that for weight gain ________, accumulated higher-intensity physical activity bouts of less than 10 minutes are quite ________, supporting the message that “every minute counts.”

When it comes to your brain, it also rings true. An April 2019 study in Jama Network Open looked at how exercise affected the brain, and even short bursts ________ 22% greater brain volume.

“Our study results don’t ________ moderate or vigorous physical activity as being important for healthy ageing. We are just adding to the science, ________ that light-intensity physical activity might be important too, especially for the brain,” Dr. Nicole Spartarno, first author of the study from Boston University said.

“I think it’s easier for people to ________ that message,” Fan says. “Otherwise, if they don’t have a block of time they might be ________, and they don’t do anything.”

10 . Loans at public libraries fell dramatically during the pandemic (疫情), while website visits rose. If the service is to ________ further cuts, it needs users.

Libraries are romantic yet plain places. The romance is that of reading, and the wealth of human imagining and learning that is ________ in them. The plain side of libraries is more ________. This is the world of buildings, shelving, books, library cards, computers — and people with bodies that ________ space as well as minds that can be opened. It would be hard to find anyone who actively ________ libraries, and question the principles of self-improvement that they stand for. But when it comes to ________, Britain’s libraries are on less solid ground. The sector has been cut ________ in the past decade, with around 800 libraries across England disappearing.

The first Covid lockdown caused a new ________ of interest in reading, as the idea took hold that people forced to stay at home would spend more time with their noses in books — both finding out more about the virus and escaping from it. But the latest data regarding libraries is ________ for anyone who values them as bricks-and-mortar (实体店) places to go. The number of books borrowed in the year ending in March 2021 was 72.9m, down 56% on the previous year. Physical visits also ________, from 214.6m to 59.7m, compared with the fact that website visits grew by 18% to 154.7m. Of course, this is the behavior that one would expect during a pandemic. Many libraries were closed during this period, when people were ________ from unnecessary mixing.

Private libraries at home, whether large collections or single, untidy bookshelves, appear to be ________, with more ones springing up. But the hope must be that visits and loans at public libraries will soon return to their former level too. Like any other service, libraries need users. And while booksellers might in one sense be regarded as rivals (竞争对手), ________ the vast majority of those involved in the trade, from publishers to poets, are library lovers — as can be seen from the volumes they have inspired.

This has something to do with the romantic notion of the reader as ________, with every book a door to a new store of feeling or understanding. But it also shows the recognition that if books are to form part of our ________ life, there must be space in public for them. Books can be treasured possessions, but there is also something special about a copy that arrives in your hands having passed through those of others — and that will go on being passed between strangers who share your curiosity.