Using technology, of course. While special services via webcam(摄像头) and cheating detecting software have been developed now, Mettl, an online company, has developed advanced techniques for netting cheaters, which the company claims are even more reliable and easier to use. Whatever small attempt to cheat, he or she will be found out.

    Mettl has adopted a handful of technologies on its test—taking platform, creating a mini monitoring state in an exam. Here's how it works: A test-takersigns on to Mettl and selects hisher exam from the site's library of pre—loaded tests. Facial and keystroke recognition technology confirm the person that has signed in is the very person, and the system records both the test—taker(through the webcam)and the test—taker's screen throughout the test.

    Mettl's technology uses the test—taker's webcam to detect how many people are using the computer. Soon, it will track eye movement well enough to sense whether the test-taker is looking away from the screen, perhaps to Consult a smart phone or a friend in secret. Mettl also monitors the test-taker's screen and can detect when the test-taker has changed a computer or moved from the test. The system will soon be able to record sound, thus detecting whether the test-taker is talking or being talked to.

    If any irregularities are detected, the system flags the incident and reports it back to the test's administrator. This can bring any number of things, depending on the test-giver's wishes: a completeshutdown of the exam, a warning message that appears on the test-taker's screen, even human instructions from the control center.

    Mettl is hoping its technology will help it break into the country's big MOOC markets.

    Professional athletes in most sports start to slow down after the age of 35. Some retire (退役). Jamaican Olympic runner Usain Bolt has talked about retiring, for example. He is only 30 years old. But on Thursday, Serena Williams earned a spot in the Australian Open finals. She will face her older sister, Venus, who won her semifinal (半决赛) match a day earlier. It is the first time that the Williams sisters will play in a Grand Slam final since 2009. Venus is 36. Serena is 35. One of them will win the championship (冠军) at last.

    One older champion will play in the men's final, too. Roger Federer qualified for the final by defeating Stan Wawrinka. Federer, like Serena Williams, is 35 years old It will be one of the sport's oldest finals in a long time.

    Ken Rosewall of Australia is the oldest winner of a Grand Slam. He was 37 when he won the Australian Open in 1972.

    Serena Williams is already the oldest winner of a women's Grand Slam match. She won Wimbledon last year at the age of 34.

    Many people are impressed that three of the finalists are 35 or older. All of the players have recently had injuries (受伤). Federer missed six months due to back and knee injuries.

    He told the crowd that he did not think he would be able to make it back to a Grand Slam final.

    The Williams sisters have had difficulties, too. Earlier this month, Venus won a match in New Zealand but withdrew (退出) from the final after hurting her arm. She also learned in 2011 she had the immune system disorder. The disorder kept her from practicing and staying in good physical condition for a number of years.

    Serena took time off to recover from knee and shoulder injuries after losing in the semifinals of the U. S. Open last September. It is the ninth time that the sisters will face each other in a major final. Serena has defeated her sister six of those times. If she wins, Serena will beat Steffi Graff's record for the most Grand Slam titles ever in women's tennis.

    Nine years ago, when the closest and largest full moon fell on March 19, 2011, many people used the term, "supermoon", which we had never heard before. In 2012, we heard this term again to describe the year's closest full moon on May 6, 2012. Supermoons also appeared in 2013, 2014, 2015, 2017 and 2019.

    What does "supermoon" mean exactly? And how special was the March 19, 2011 supermoon?

    The word "supermoon" didn't come from astronomy. Instead, it came from astrology (占星学). In 1979, astrologer Richard Nolle defined it as a new or full moon which occurs at or near its closest point to the earth in its orbit. In short, the earth, moon and sun are all in a line, with the moon at its nearest point to the earth.

And the full moon of March 19, 2011 was the largest moon of that year. This "supermoon" was at perigee (近地点) — its closest point to the earth in its orbit. It was bigger and brighter than other full moons of 2011. Astronomers call this sort of close full moon a perigee full moon.

    That doesn't sound very special, does it? In fact, the March 2011 full moon lined up much more closely with perigee than Nolle's original definition. But were you able to notice with your eyes alone that this full moon was bigger or brighter than usual? Astronomers said no. But it was fun to stand outside under this full moon and know that the moon was closer than ever.

    In 2019, there were three supermoons. The first supermoon of 2019 was the Super Blood Wolf Moon on January 21, which occurred with a total lunar eclipse (月全食) at the same time, also known as a "blood moon". The second supermoon of 2019 was on February 19, also called the Snow Moon, which was the closest full moon of the year. The third and final supermoon of 2019, known by Native Americans as the Worm Moon, occurred on March 21. It fell on the day of the vernal equinox (春分), which signals the end of winter and the beginning of spring.

A recent story on TikTok showed how two neighbors found companionship (陪伴) and a new spirit in life during COVID-19, thanks to a shared love of the piano.

The heartbreaking story started when Giorgio Lo Porto heard his neighbor playing the piano through their dividing wall. Lo Porto is an Italian living in London. He reached out to his neighbor and left a note, saying if he or she could play My Heart Will Go On. The mystery neighbor agreed, suggesting they play together. Over time the music between two complete strangers became a regular weekend engagement(约会).

A week later, the pair finally met and "it was better than expected," shared Lo Porto. The mystery pianist happened to be a78-year-old Polish man named Emil. "He lost his wife in December due to COVID-19 and all he has been left is the piano. And he plays at 2 p.m. every weekend because his wife loved it," shared Lo Porto.

While Emil didn't want to appear on any of the videos, he did share his thankfulness to Lo Porto for keeping him motivated during a most emotional and lonely time.When the pair offered each other company, Emil also inspired Lo Porto to continue writing his own song. And Emil reported being happier after playing music with Lo Porto and was thankful to those who watched their performance.

The bittersweet story shows the unbelievable influence two complete strangers can have on each other. Emil moved out at the end of February. Lo Porto wrote, "Dear Emil, you changed my life. You gave me back my passion (激情)，and we shared that with the world. You'll be in my heart. I'll keep playing, thinking of how powerful music can be. You said I was your light, but you've been mine too. Bye, Emil."

High on the Qinghai-Xizang Plateau {#blank#}1{#/blank#}(lie) China's "water tower" Sanjiangyuan. It is home to the headwaters of China's three rivers: the Yellow River, Yangtze River, and Lancang (Mekong) River. It is the three rivers {#blank#}2{#/blank#} provide water for about half the population of China. However, human activities are putting this ecosystem {#blank#}3{#/blank#}risk. Hopefully, though, we can change this damage. In 2016, the Chinese government built Sanjiangyuan National Park in Qinghai province. The park, {#blank#}4{#/blank#}(schedule) to open in 2020, has increased the area's green coverage and attracted more wildlife. The local government has also made great effort to improve biological diversity. The success of Sanjiangyuan will mark the start of a {#blank#}5{#/blank#}(green) future. With Sanjiangyuan {#blank#}6{#/blank#}(take) the lead, nine other regions in China {#blank#}7{#/blank#}(choose) by a field conservation station to carry out projects over the past three years, {#blank#}8{#/blank#} will form a national park system together. The idea of a national park system is still new in China, but{#blank#}9{#/blank#}(it) realization is urgent. After all, building an ecological civilization bears great{#blank#}10{#/blank#}(important) in the development and progress of human civilization.