We produce 500 billion of plastic bags in a year worldwide and they are thrown away polluting oceans, killing wildlife and getting dumped in landfills where they take up to 1,000 years to decompose. Researchers have been unsuccessfully looking for a solution.

    The 16-year-old Canadian high school student, Daniel Burd, from Waterloo Collegiate Institute, has discovered a way to make plastic bags degrade(降解) in as few as 3 months, a finding that won him first prize at the Canada Wide Science Fair, a ＄10,000 prize, a ＄20,000 scholarship, and a chance to revolutionize a major environmental issue.

    Burd's strategy was simple: Since plastic does eventually degrade, it must be eaten by microorganisms(微生物)．If those microorganisms could be identified, we could put them to work eating the plastic much faster than under normal conditions.

    With this goal in mind, he grounded plastic bags into a powder and concocted(调制) a solution of household chemicals, yeast(酵母) and tap water to encourage microbes growth．Then he added the plastic powder and let the microbes work their magic for 3 months．Finally, he tested the resulting bacterial culture on plastic bags, exposing one plastic sample to dead bacteria as a control．Sure enough, the plastic exposed(暴露) to the live bacteria was 17% lighter than the control after six weeks.

    The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide.

    “Almost every week I have to do chores and when I open the closet door, I have piles of plastic bags falling on top of me．One day, I got tired of it and I wanted to know what other people are doing with these plastic bags．The answer: not much．So I decided to do something myself.” Said Daniel Burd.

    “Soon, you're going to have to move out!” cried my neighbor upon seeing the largest tomato plant known to mankind, or at least known in my neighborhood.

    One tiny 9-inch plant, bought for $1.25 in the spring, has already taken over much of my rose bed, covering much of other plants, and is well on its way to the front door.

    Roses require a good deal of care, and if it weren't for the pleasure they give, it wouldn't be worth the work. As it is, I have a garden full of sweet-smelling roses for most of the year. bushes must be pruned(剪枝) in early spring, leaving ugly woody branches until the new growth appears a few weeks later. It was the space available(可用的) in the garden that led me into planting just one little tomato plant. A big mistake.

    Soil conditions made just perfect for roses turn out to be even more perfect for tomatoes. The daily watering coupled with full sun and regular fertilizing(施肥) have turned the little plant into a tall bush. The cage I placed around it as the plant grew has long since disappeared under the thick leaves.

    Now the task I face in harvesting the fruit is twofold; First, I have to find the red ones among the leaves, which means I almost have to stand on my head, and once found I have to reach down and under, pick the tomatoes and withdraw(缩回) my full fist without dropping the prize so dearly won. I found two full-blown white roses completely hidden as I picked tomatoes in June, but they were weak and the leaves already yellow for lack of light.

    Here I am faced with a painful small decision: To tear up a wonderful and productive tomato plant that offers up between ten and twenty ripe sweet tomatoes each day or say goodbye to several expensive and treasured roses. Like Scarlett in Gone With the Wind, I'll think about that tomorrow.

    The arts, especially music, should be part of every school's lessons at every grade level. Students would be much smarter if they had some musical experience. They could improve their classroom skills, like paying attention and following directions. People develop all these skills when they learn music. Making music also lets children use their imagination. It provides students with a chance to try out their own ideas.

    Music not only makes children better students, but also gives them something positive to do. In a music program, children can be part of a band instead of joining a gang (团伙). Parents can enjoy listening to their children's music instead of seeing them glued to a computer or TV screen. In a school band, students get to be part of a team. They can get along well with old friends and make new friends through music.

    Music builds self-confidence, too. It gives children a sense of achievement and success. Making music is something for them to be proud of, and it lets kids practice performing in front of an audience. Music gives children an opportunity for self-expression, and that helps develop their self-confidence.

    Once again, music is important because it can make children better students, give them something positive to do, and build their character. That is why music should be offered in every single grade in every school.

    Stars blazed(猛烈地燃烧)in the sky above Spook like a million tiny suns. They shone through the mists, which had during the last year become thinner and weaker. At first, he had thought the world itself was changing. Then he had realized that it was just his feeling. Somehow, by burning tin in his body for so long, he had permanently strengthened his senses to a point far beyond what other Allomancers could attain.

    The burned tin had begun as a reaction to Clubs's death. Spook still felt terrible about the way he'd escaped, leaving his uncle to die. During those first few weeks, Spook had burned his metals as almost a self-punishment he'd wanted to feel everything around him, take it all in, even though it was painful, or perhaps because it was painful.

    But then he'd started to change, and that had worried him. But, the crew always talked about how hard Vin pushed herself. She rarely slept, using pewter(白镴)to keep herself awake and alert. Spook didn't know how that worked he was no Mistborn, and could only bum one metal but he figured that if burning his one metal could give him an advantage, he'd better take it, because they were going to need every advantage they could get.

    The starlight was like daylight to him. During the actual day, he had to wear a cloth tied across his eyes to protect them, and even then going outside was sometimes blinding. His skin had become so sensitive that each little stone in the ground felt like a knife jabbing(猛刺)him through the bottom of his feet. The cold spring air seemed freezing, and he wore a thick cloak(斗篷).

    However, he had concluded that these discomforts were small prices to pay for the opportunity to become whatever it was he had become. As he moved down the street, he could hear people turning over and over in their beds, even through their walls. He could sense a footstep from yards away. He could see on a dark night as no other human ever had.

       ①   Always before, he'd been the least important member of the crew the dismissible boy who served as a handy man or kept watch while the others made plans. He didn't feel annoyed with them for that he'd been right to give him such simple duties.   ②    Because of his street dialect, he'd been difficult to understand, and while all the other members of the crew had been carefully picked, Spook had joined through the back door since he was Clubs's nephew.

    Spook sighed, sticking his hands in his trouser pockets as he walked down the too-bright street. He could feel each and every thread of the cloth.

    Dangerous things were happening he knew that: the way the mists lasted longer during the day, the way the ground shook as if it were a sleeping man, periodically(周期性地)suffering a terrible dream. Spook worried he wouldn't be of much help in the critical days to come. A little over a year before, his uncle had died after Spook fled the city. Spook had run out of fear, but also out of a knowledge of his lack of power.   ③    He wouldn't have been able to help during the campaign.

    He didn't want to be in that position again. He wanted to be able to help, somehow. He wouldn't run into the woods, hiding while the world ended around him. He was sent to gather as much information as he could about the Citizen and his government there, and so Spook intended to do his best. If that meant pushing his body beyond what was safe, so be it.

    He approached a large crossing. He looked both ways down the intersecting(交叉的)streets the view clear as day to his eyes. I may not be Mistborn, and I may not be emperor, he thought. But I'm something. Something new. Something people would be proud of Maybe this time I can help.   ④    

    When I was about 5 years old, I experienced my very first random act of kindness. I was sitting at the roadside one evening, crying alone for some reason when suddenly, a boy came up to me and gave me a plastic rose, I remember the moment when I took the rose from his hand; I was smiling from ear to ear, whispering "I want to be like him" to myself as I watched him walking away.

    From then on, I made it as my life mission to do random acts of kindness whenever I can. I was very determined to make other people smile. That was the only reason why I joined my school's Red Crescent Society and became a volunteer. Unfortunately, not everyone thinks in the same way as I did. Whenever I do something nice to others, people around me will start to judge my actions. Often I will just keep quiet and ignore what they say, but every once in a while, they do drive me up the wall.

    These people like to complain about how humans nowadays are lacking of humanities and compassion. However, when they actually see somebody doing a good deed in front of them, they start to question and criticize that person's honesty. Perhaps it is the increasing crime rate and the never-ending rat race that caused them to be so suspicious to nice strangers. In other words, people nowadays have lost sight of the real meaning of kindness and just let it go unnoticed. That is why I think random acts of kindness are really important. These selfless acts are not only capable of bringing joy to the receivers but also to the givers. Because of this, I want to help spread the idea of these random acts to the whole world. I want to show the people how the little things they give could make a big difference in someone else's life.

A 293-million-mile journey of the NASA Perseverance rover (探测器) to Mars: ended successfully on February 18, 2021, with a picture-perfect landing inside the Jezero Crater. The car-sized, six-wheeled rover, nicknamed Percy is the US space agency's biggest and most advanced explorer to date. Its primary mission is to search for signs of ancient microbial (微生物的) life on Mars.

Landing on Mars is extremely tricky. The Red Planet's gravitational pull causes approaching spacecraft to go faster to high speeds, while its thin atmosphere-just 1 percent that of Earth's-does little to help slow it down as it approaches the surface.

The scientists had to reduce Percy's 12,000 mph speed to a safe landing speed of less than five mph-in just six and a half minutes. The target entry angle also had to be a precise 12 degrees-any steeper, and the spacecraft would burn up; any flatter, and it would get lost in space. It is no wonder that the final approach is often referred to as the "seven minutes of terror. "

Upon attaining a manageable speed, Percy briefly flew over the Martian surface to seek out the perfect landing spot. Its complex map-reading system rapidly scanned the area and matched it with maps in its database to find the best location.

The NASA scientists will spend the next two months testing Percy's scientific instruments. Once ready, the rover will begin to carry out its mission.

"Perseverance is the smartest robot ever made, but confirming that microbial life once existed carries an unusually large burden of proof," said Lori Glaze, director of NASA's Planetary Science Division. "While we'll learn a lot with the great instruments we have aboard the rover, it may very well require the far more well-equipped laboratories and delicate instruments back here on Earth to tell us whether our samples (样本) carry evidence that Mars once harbored life. "