1 . The World Health Organization says it believes between 80,000 and 180,000 health care workers may have died from COVID-19 in the period between January,2020 and May, 2021. In a ______ issued Thursday, the group ______ those deaths are tragic loss and an irreplaceable gap ______ the world’s pandemic response. It said the reported ______ of infections and deaths among health ______ workers has gone down ______ time but added that more work needs to be done to ______ the risk of infection in the health carework place. It said as of September, 2021 ______ data from 119 countries, only an average of two and five health care workers were ______ vaccinated. It said fewer than one in ten are fully vaccinated in the African and Western Pacific regions ______ 22 mostly high-income countries report that above 80 percent of their personnel are fully vaccinated. WHO said it is deeply concerned about the probable number of deaths, the overall low rate of vaccinations and the vaccinein equities among health care workers in low- and middle-income countries.

The COVID-19 pandemic (流行病) reduced global greenhouse gas emissions by 7 percent this year, released by the Global Carbon Project on Friday.

“The amount fell by 2.4 billion metric tons    1    the current level of 34 billion metric tons of carbon dioxide (CO2)”, said the study    2    (publish) in the journal Earth Systems Science Data. “The drop occurs    3    (chief) because people are staying home and traveling    4    (little) by car and plane, and emissions    5    (expect) to jump back up after the pandemic ends”, the research team said. The data show that ground transportation makes up about one-fifth of emissions of carbon dioxide. Though the record    6    (drop), the world on average put 1,075 metric tons of CO2 into    7    air every second. The scientists of the study said that long-term emissions trends would be heavily influenced by how    8    (country) power their pandemic recovery plans.

UN Secretary-General Antonio Guterres on Tuesday appealed for ambitious climate action,    9    (say) 2021 must be the year    10    the world leaps forward into a net-zero emissions future.

3 . Students in the class of 2021 have faced unusual challenges. The global COVID-19 pandemic forced schools and students to make big changes. In 2020, the pandemic led to the cancellation (取消) of many special events like prom and graduation.

Students of the class of 2021 at Newton North High School in Newton, Massachusetts, think this spring can be different. They are working to keep students connected and traditions alive. Kevin Wu, the class president, and other student leaders have hosted events like a kickball match and a free movie night. In other years, the student union puts on events to raise money. Now, though, the events are about keeping the senior class connected.

Newton North is planning an in-person prom for the class of 2021. As part of the COVID-19 safety rules, the prom is taking place outdoors in a field. Students said they have gotten used to the idea that it won’t be what they once expected. They are thankful for the experience.

“I think to some extent we all didn’t think we were going to have a prom. It was a pleasant surprise,” said Sara Sales, a senior. “I think everyone’s pretty happy just to have the opportunity to be able to participate in an event like that, and bring everyone together.”

Ellie Solomon is a senior at Newton North. She said she was excited to dress up and connect with friends. Sanders said the class of 2021 has done well adjusting to the changes. He said, “We look forward to celebrating what we can celebrate at the end of the year and enjoying every minute of it.”

Graduation and prom symbolize an end for seniors. Sales thinks her class is ready, though. “I feel like everyone’s just ready to graduate,” she said. “We’ve gone through a crazy year, and I think we’re all sort of ready to just move on and go to college.”

5 . “The Delta variant is the most able, fastest and fittest of the coronavirus variants,” said Mike Ryan, executive director of the World Health Organization’s Health Emergencies Program. And the USA’s top health officials said recently that the Delta variant is racing through the country and now is responsible for 83% of all USA cases. So what makes the variant so horrible？

The Delta variant was first identified in India in spring this year. In just a few months’ time，it has spread across the globe. Research from the United Kingdom shows that the Delta variant is highly contagious(传染的). It’s about 60% more easily passed from person to person than the Alpha version, which was first identified in the UK. While a single infected person might have spread older versions of the virus to two or three others, number—called the basic reproduction number—might be around six for Delta, meaning that, on average, each infected person spreads the virus to six others.

Early evidence suggests the Delta variant may cause more severe disease in people who are not vaccinated. In fact, it has raised the risk even higher, increasing the odds that an infected person would need to be hospitalized or could die from their infection by 50% compared to older variants, regardless of vaccination status.

Emerging evidence from England and Scotland, analyzed by Public Health England, also shows an increased risk for hospitalization with Delta. The Delta variant has about 15 different mutations(突变) compared with the original virus. Two of these mutations can help the virus escape the antibodies we make to fight it.

It has another mutation that is also getting researchers’ attention—known as P681R. This mutation appears to help the virus get into our cells. So it’s more likely to be in the right position to infect our cells if we come into contact with it.

P681R may also enhance the virus’ ability to unite cells together to be clumps(团块). These clumps of cells are called syncytia(合胞体). They turn into a big factory for making viruses. Scientists aren’t sure what these supersized syncytia mean exactly, but they have some theories. They may help the virus copy itself more rapidly. That may enhance the ability of the virus to transmit from person to person. At least one recent study from China supports this idea. That study tracked 167 people infected with the Delta variant back to a single case.

Scientists say that what we already know about the Delta variant makes vaccination more important than ever.

6 . As COVID-19 broke out and spread in the world, many countries are changing their social habits to reduce the risk of spreading the novel coronavirus(新型冠状病毒）.Here are some of the ways that greeting habits are changing around the world.

China

Loudspeakers tell people not to shake hands but to make the traditional gongshou gesture(a fist in the opposite palm)to say hello.

France

France is famous for its romantic greetings.They touch each other's cheeks and make a kissing sound. But now, this habit may be coming to a stop. News papers in France have begun publishing advice on how to replace kissing on the cheek. French etiquette(礼仪）expert Philippe Lichtfus said that simply looking into a person's eyes can be enough as a greeting.

Spain

The outbreak could also hit one of Spain's most important traditions---in the week before Easter, known as Holy Week,the faithful(信徒）queue up to kiss the hands or feet of sculptures of the Virgin Mary and the saints,seeking their protection. It's said that the ceremony could be banned.

Iran

7 . What one word reflects the unprecedented(史无前例的) year of 2020 and is closely related to our lives ? Based on readers’ suggestions, we have five words as candidates for you to vote on for China Daily app’s 2020 Word of the Year. A grand prize will be awarded to 10 participants whose choice is voted as China Daily app’s Word of the Year.

To help stop the spread of coronavirus, health officials recommend avoiding large gatherings and maintaining a distance of 1-2 meters from other people. Social distancing places no such location constraints; rather, it is a behavioral practice to lower the risk in most circumstances.

A number of companies asked their employees to work from home, with some of them having carried out remote work policies. This unexpected experiment has been so well-received that employers are considering adopting it as a more fixed measure. For some digital-based sectors, working from home has instead been surprisingly effective.

Everybody has been trying to recover from the impact of COVID-19 in 2020 by remote working, online education, social distancing and more. Countries suffering from the coronavirus are trying to recover. Many of them have promoted tax and fee reductions, improved the business environment, and inspired the enthusiasm of market players.

The World Health Organization declared in March that the spread of COVID-19 had become a pandemic. More than 200 countries and territories around the world have reported confirmed cases of the coronavirus. Global health authorities and vaccine developers are currently partnering to support the technology needed to produce vaccines(疫苗).

It was a year when the whole world had to collaborate and work together in unity to overcome challenges faced by all of mankind. Some of these major events include severe natural disasters, economic recession（衰退）and COVID-19. These events have brought the world closer, allowing billions of people across the world to experience the true power of a united mankind.

Yours,

Li Hua

10 . Vaccines(疫苗) against COVID-19 are about 90 percent effective at blocking coronavirus infections, studies suggest.

Nearly 4,000 health care workers, first responders and firefighters in six states took part in the study led by CDC researchers. From December 14 through March 13, the workers submitted weekly nasal swabs(鼻拭子) for coronavirus testing. Infection rates fell after vaccination. “Our study shows that if you were fully vaccinated, you had 90 percent protection from infection”, says Jeff Burgess.

Other studies carried out in California and Texas also seem to back up the findings, researchers say in separate reports published March 23 in the New England Journal of Medicine. In the Texas report, 234 of 8,969 non-vaccinated employees at the University of Texas Southwester Medical Center in Dallas tested positive for the coronavirus from December 15 to January 28. That’s 2.61 percent, compared with 1. 82 percent (112 of 6, 144) of employees that had gotten one shot and 0. 05 percent (four of 8, 121) of fully vaccinated employees.

In the California report, infections among health care workers also fell with increasing vaccination levels. Only seven infections occurred among 4, 167 people who were at least 15 days out from getting their second dose of vaccine. The vaccines prevented health care workers in the study from becoming serious ill, says study coauthor Francesca Torriani, a professor at the University of California, San Diego.

But to really stop transmission of the virus, it’s important to vaccinate 18- to 30-year-olds, she says, “Those are the ones who are right now transmitting the disease.” Motivating these health people who are less likely to become severely ill in the first place to take the shots could be difficult, Torriani says, “There’s not much in it for them, but there is a lot in it for their families, so I’m hoping that realization will push them toward getting vaccinated.”

Because some vaccinated people can still get infected, the CDC recommends that people who have gotten their shots continue to wear masks in public to avoid spreading the virus.