If you walk through a park, you may enjoy the scents(气味）of flowers, water and soil. If you are especially lucky, you will get to smell fresh-cut grass. It's a beloved scent that transports many people back to their childhood. But there's a dark side to that smell. Indeed, we are in love with the scent of fear.
Plants have many different chemical defenses. That smell is one of them, as the grass responds to an attack, signaling(向......示意）to the surrounding grass that danger is coming. The fresh, "green” scent of a just-mowed lawn is the lawn trying to save itself, says a story at science website Real-Clear Science.
The smell is produced by a mix of chemicals called green leaf volatiles(GLVs, 绿叶挥发物）. When the leafy plants are injured by animals eating them, people cutting them, or any other rough treatment-they give off GLVs into the air. These GLVs are a warning to neighbouring plants that their flowers might be removed, so they can move resources like sugar toward their roots and away from their flowers. This reduces a plant's potential losses and can help it grow back later.
The rush of GLVs does a few other things, too. One chemical helps to close the wound on the damaged plant. Others act as antibiotics(抗生素）and prevent bacterial infections.
Some GLVs may also react with animals that eat plants. Silke All-mann and Ian T.Baldwin, researchers from the University of Amsterdam, Netherlands, found that some caterpillars(毛虫）are changed by the GLV compounds(化合物）when they eat a tobacco plant. Tobacco makes the caterpillars more attractive to predators(捕食者）. For the tobacco plants, this is like having an older brother come to beat up your bully(欺凌者）.
Thankfully, nothing is coming to eat you when you mow the lawn. Instead, we human get treated to some great-smelling GLVs. One is a compound known as"cis-3-hexenal". This is the same chemical that gives strawberries their sweet scent. Similar compounds are also found in apples and olives.
＂Just about all fresh vegetables have some GLV scents to them," Baldwin told Live Science, and fruits may release the compounds as they soften." Throughout evolutionary history, we've used that information to know when something is ripe," Baldwin said. Now we can use it to know when grass is frightened.
You know the old phrase, "Practice makes perfect. "That may not always be true. According to a recent study published in Royal Society Open Science, there are other factors for reaching elite(最优秀的）levels of ability.
The researchers set out to replicate(复制）the process of a new-famous 1993 study of top-level violinists and pianists. On average, the earlier study found that top-ranked musicians had clocked over 10,000 hours of practice by the age of 20. It put their success down to the hours spent practicing, downplaying the importance of natural, learning skills and other factors.
Author Malcolm Gladwell later relied on this study for his 2008 book, Outliers. He called 10,000 hours "the magic number of greatness".
Questioning this conclusion, Brooke Macnamara and Megha Maitra, from Case Western Reserve University in Ohio, US, sought volunteers to put the 10,000-hour rule to the test.
The pair organized violinists into three groups, based on whether their tutors rated them as the best players, good players, or average players. They were then told to record how long they practiced every week.
They found that the “average” players had around 6,000 hours of practice. However, there was little separating the good from the best musicians. Both groups had approximately 11,000 hours of practice by the age of 20. In all, the number of hours spent practicing accounted for about a quarter of the skill difference across the three groups.
＂Once you get to the highly skilled groups,practice stops accounting for the difference," Mannamara told the Guardian. "Smaller factors then determine who goes on to that superelite level."
＂The factors depend on the skill being learned: in chess it could be intelligence or working memory, in sport it may be how efficiently a person use oxygen," she said. She also pointed out the factor of motivation and the interactions of different factors.
Ralf Krampe, a co-author of the 1993 study, disagrees, saying the quality of practice and teaching does matter.“....I still consider deliberate(刻意的）practice to be by far the most important factor," he told the Guardian.
It should be said that neither side discounts the value of making an effort. Even if you aren't destined（命中注定）to be the world's greatest violinist, practice will make you a little bit better than you were yesterday.
Living gratefully has a huge transforming power, not just when something wonderful or special happens, but every day no matter what is happening.
I've recently been involved with two people whose lives were challenged by bad luck. I have seen how grateful living had the power to keep one of them going and how it's beginning to lift the other. One was a friend and the other is my sister.
My friend seemed to be in good health when she received a deadly diagnosis(诊断）: a disease with no effective treatment. She had all the emotions that a tragedy(悲剧）brings, but she also had a powerful response to despair that gave her"the happiness that doesn't depend on what happens." She wrote online daily, honestly sharing the details of her situation.
She wrote that even though it was difficult to move, this gave her more time to notice small things.
She was grateful not only for the love and help of family and friends, but also for time to see the sun rise and watch the birds in her yard. No opportunity for gratefulness was wasted.
She taught that gratefulness is not a false cheerfulness. It's taking every opportunity to celebrate the blessings of small things. We can be grateful for the challenges that help us develop compassion(同情）for each other. Life is a precious gift.
She repeatedly blogged(写博客）that she was happier than she had ever been.
When she wrote about "the worst day", she ended with "life is still a lovely gift." She died later that day.
Her message, however, changed my sister's life. My sister's health was getting worse and worse, though nothing life-threatening. She did have a very painful knee. Her life was in danger from her defeated spirit. She was bedbound(卧床不起），getting weaker and weaker. Fearful, angry and depressed, she felt out of options for recovery.
I read my sister a few of my friend's messages. I was careful not to say, "Why can't you be more like her?" Instead, I let the words do their work. I'm grateful to say that an attitude of gratitude began to replace her anger and fear. I believe this helped her to heal.
We can't be grateful for all that happens, but we can practice gratefulness for all that happens, but we can practice gratefulness for life itself, for all we can learn to deal with, for all the ways we can help each other grow and heal.
Lessons learned in past outbreaks
The novel coronavirus dominates(主导）the headlines as one of the world's most pressing issues. It has killed more people than the 2003 SARS outbreak, according to the World Health Organization（WHO).?
One of the biggest lessons from SARS was to share the latest information about the virus with the public and other countries in the world as quickly as possible., allowing scientists around the world to start developing a vaccine(疫亩）on Jan 12, according to Xinhua.
With experiences of fighting against SARS and MERS, many countries were also better prepared to stop the spread of coronavirus..During the 2012 MERS outbreak, research showed that infected camels caused the outbreak. According to the WHO, strict measures were enacted(实施）, restricting the sale of camels and camel products in the Arabian Peninsula. There were also mass health tests for all those in close contact with diseased animals.
In the fight against the novel coronavirus, China has also taken many effective measures to control the virus. Under the leadership and command of the central government, all provinces and municipalities(自治区）across the country have launched a Level One emergency response to the novel coronavirus.. It is because of these effective measures that the epidemic has been constrained （限制）successfully within China, with the confirmed cases less than many other countries.
A. They also quickly isolated (隔离）those who were confirmed infected for medical care
B. Chinese health officials published the details of the new virus online
C. The number of infections overall in China are now far more than that of SARA
D. Following the measures, the number of the infected has dramatically decreased
E. The outbreak has killed many people since the first death was reported in Wuhan
F. But there is no better prevention than stopping the source
G. What can we learn from the past outbreaks, including SARS and MERS
One day in May 1884, twenty-one-year-old Ida Bell Wells 1a train for Woodstock. Ida sat in the first-class ladies'2 and opened her book. Minutes later the conductor 3 passengers' tickets. He told Ida to go to the other carriage.
In 1884, African Americans, 4in the South, did not have the same 5 as whites. They could not 6the same schools and they were expected to sit in a(n) 7 railroad carriage, one that was usually dirty and smoke-filled, though they were charged 8 fare.
Having paid for a first-class ticket, Ida refused to 9. Then the conductor, together with two other railroad men, 10 Ida from her seat, tearing her sleeve. After she was11out of her seat, Ida sued(起诉）the Chesapeake and Ohio Railroad. When the case went to 12, the judge decided in Ida's favor. He 13 her 500 dollars in damages. But Ida's 14 did not last long. The Chesapeake and Ohio Railroad appealed its case. This time, the victory went to the railroad.
Ida had lost her 15with the railroad, but not her determination to 16what was right. After losing her case, Ida wrote an article about it, which 17in a number of African American newspapers. Readers quickly recognized the 18 of Ida's words.
In 1913, Ida came to Washington, D.C.as a journalist. There she became a representative of the National Equal Rights League. The league 19 President Woodrow Wilson to end segregation(种族隔离）. Ida didn't live to see the end of segregation, but she did help lead the way in bringing about 20for all.
The historical drama, Serenade of Peaceful Joy has been a trending topic since it (release) on April 7. It has attracted almost 7.5 billion views and over 190, 000 comments on Sina Weibo by May 5.
The show is an (adapt) from the novel Held in the Lonely Castle written in 2014 by Milan Lady, with (vary) editions published since 2008. The story follows Emperor Renzong, (play) by Wang Kai, of the Song Dynasty(960-1279) as he struggles maintaining his ideologies of governing the country and his love for his daughter, Princess Huirou.
The four-decade reign of Emperor Renzong, from 1022 to 1063, (mark) the high point of Song Dynasty's powers has great influences on Chinese history. Many of the best-known (write) in Chinese history lived during this period, some of including Su Shi, Wang Anshi and Fan Zhongyan are featured in the series.
A few days after its premiere(首映），show is highly praised for its outstanding props, costumes, make-up and writing, which (accurate) portrayed the features of the Song Dynasty.
1）简单介绍该项活动；
2）志愿者所需条件.
注意：
1）词数80左右；
2）可适当增加细节，以使行文连贯.
Artificial intelligence(AI) teachers can provide customized teaching for students to meet their unique requirements through analyzing data and deep learning.In the future, they may replace human teachers for basic teaching tasks. Since some students may find it and put new power into traditional teaching patterns. An educational system providing customized teaching centered on students represents the future trend of AI education.
China's AI education has developed rapidly in recent years with the rise of several thousand relevant companies. Currently, AI teachers are able to help students leamn pronunciation, analyze their condition, guide them to learn independently, and even grade writing assignments. Some foreign AI educational systems have been introduced into several domestic schools and have worked well on trial.
However, the promotion of AI education is still facing several difficulties in practice such as low technological levels, inadequacy of data and lack of funds.AI education still depends largely on human teachers' work. Most importantly, it conflicts with current educational patterns because the courses developed by foreign countries are not suitable for Chinese exam-oriented education. Teachers may also find it hard to change their original roles in classrooms since easing control on classes may make them seem irresponsible. These problems need to be handled before the mass promotion of Al education.
With AI teachers, the original teacher-centered classes will be transformed into student-centered ones where teachers only organize the class and provide guidance. Since teachers are supposed to not only equip students with knowledge but also shape their values and help them develop creative abilities, AI teachers will not replace human teachers but will only pose higher requirements of teaching. A combination of AI teachers and human ones can create the best future for Al education.
