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.

Do you dream?

    Have you ever visited some strange places in your dreams? In fact people have wondered about these strange places for long.{#blank#}1{#/blank#} However, they have been valued as necessary to a person's health and happiness.

    Historically, people thought dreams contained messages from God. It was only in the twentieth century that people started to study dreams scientifically, believing that they tell about a person's character.{#blank#}2{#/blank#} He believed that dreams allow a person to express fantasies or fears, which would be socially unacceptable in real life.

    The second theory to become popular was Carl Jung's compensation theory. Jung, a former student of Freud, said that the purpose of a dream is not to hide something, but rather to communicate it to the dreamer.{#blank#}3{#/blank#} Thus, people who think too highly of themselves may dream about falling; those who think too little of themselves dream of being heroes.

    Using more recent research, William Domhoff from the University of California found that dreaming is a mental skill that needs time to develop in humans.{#blank#}4{#/blank#} Until they reach the age of five, they can not express very well what their dreams are about. Once people become adults, there is little or no change in their dreams. The dreams of men and women differ. For instance, the characters that appear in the dreams of men are often other men, and often involve physical aggression.

    The meaning of dreams continues to be difficult to understand. {#blank#}5{#/blank#} If you dream that a loved one is going to die, do not panic. The dream may have meaning, but it does not mean that your loved one is going to die.

A. Dreams make up for what is lacking in waking life.

B. But anyway, people should not take their dreams as reality.

C. It gives scientists chances to better understand human mind.

D. They have been considered as meaningless nighttime journeys.

E. First, there was Sigmund Freud's theory.

F. They think their mind is trying to tell them something.

G. Children do not dream as much as adults.

    Traffic Light Reading is one of students' favorites! And it's so simple. Here's what to do: Take three pens in different colors, most suitably red, orange and green. But it's not too important as long as teachers and students are both clear on the colour code they're going to use.

    Students read a text, not worrying too much about how much they understand. Teachers can ask them to re-read when students are paying attention to vocabulary. Start by underlining the words that they understand completely (including names, numbers etc) in green.

    Then students re-read the text and underline the words that look familiar-they maybe know them but aren't too sure about them. You guessed it: in orange.

    Finally, students read the text a third time underlining the words they clearly don't understand in red. Sometimes teachers might want to set students a limit for how many red words they underline, telling them only to underline the words that they believe are seriously blocking their understanding of the text as a whole. Generally, however, students are pleasantly surprised by how few words are red and how many are green. Seeing their ability laid out in a visual way really helps to increase confidence.

    Once the whole text is underlined, teachers can give students a limit of 5, 10 or 15 words, depending on the length of the text, and tell them they're only allowed to look these words up in a dictionary. This helps them to recognize words that are actually getting in the way of their understanding of the text and words that they don't know but actually don't impact their whole understanding of the text.

    This is a useful activity that can be done with a printed text, in a Google Doc, on RealtimeBoard, or set as a homework task for some independent study.

    Many of us love July because it's the month when nature's berries and stone fruits are in abundance. These colourful and sweet jewels form British Columbia's fields are little powerhouses of nutritional protection.

    Of the common berries, strawberries are highest in vitamin C, although, because of their seeds, raspberries contain a little more protein (蛋白质), iron and zinc (not that fruits have much protein). Blueberries are particularly high in antioxidants (抗氧化物质). The yellow and orange stone fruits such as peaches are high in the carotenoids we turn into vitamin A and which are antioxidants. As for cherries (樱桃), they are so delicious who cares? However, they are rich in vitamin C.

    When combined with berries of slices of other fruits, frozen bananas make an excellent base for thick, cooling fruit shakes and low fat “ice cream”. For this purpose, select ripe bananas for freezing as they are much sweeter. Remove the skin and place them in plastic bags or containers and freeze. If you like, a squeeze of fresh lemon juice on the bananas will prevent them turning brown. Frozen bananas will last several weeks, depending on their ripeness and the temperature of the freezer.

    If you have a juicer, you can simply feed in frozen bananas and some berries or sliced fruit. Out comes a “soft-serve” creamy dessert, to be eaten right away. This makes a fun activity for a children's party; they love feeding the fruit and frozen bananas into the top of the machine and watching the ice cream come out below.

    A five-year-old dog named Kelsey has been praised as a hero for helping to save the life of her owner who slipped in the snow and broke his neck.

    The man, Bob, was alone when he left his Michigan farmhouse on New Year's Eve to collect firewood. Expecting a journey of only several meters, Bob was wearing just long johns (衬裤), a shirt and slippers when he went outside, although the temperature was around -4℃.

    After the accident, he was unable to move in the snow. Fortunately, Kelsey came to his assistance.

    "I was shouting for help, but my nearest neighbor is about 400 meters away, and it was 10:30 pm, Bob explained." But my Kelsey came. By the next morning, my voice was gone and I couldn't yell for help, but Kelsey didn't stop barking."

    Kelsey's companion kept him warm by lying on top of him. She licked his face and hands to keep him awake." Kelsey kept barking but never left my side," Bob recalled. "She kept me warm. I knew I couldn't give up and that it was my choice to stay alive."

    Bob spent 20 hours in the freezing cold. When he finally lost consciousness, his dog kept barking. Finally, hearing the barking, Bob's neighbor discovered him at 6:30 pm on New Year's Day and called the emergency services at once. When Bob arrived in hospital, his body temperature was below 21℃. However, doctors were surprised to find that he didn't have any frostbite (冻疮). They believed it was because of Kelsey's determination to keep him warm, Dr. Chaim Colen, the doctor who treated Bob, said, "Animals can help and his dog really saved him... He was very fortunate.”

    Bob said he was "enormously" grateful to both Dr. Colen and his Kelsey, "They saved my life. They are truly heroes!"

    Nowadays six Amazon Scout delivery robots rolled out in a pilot program in Snohomish County, Wash. The robots carry meals, groceries and packages to homes and offices in this region just north of Seattle. They have appeared on the sidewalks of London, Beijing and other cities and communities worldwide. These machines must overcome pedestrian legs, naughty dogs and broken pavement, which raises some questions.

    These services are gaining attraction as a growing number of city residents expect immediate or scheduled delivery for just about everything. Between 2017 and 2018 online retail sales in the U.S. increased by 16 percent. On the final step of all these deliveries, called the last mile, humans on bicycles, motorized scooters (电动车) or large delivery trucks typically deliver packages. All the vehicles compete for space on busy urban streets. "Deliveries are trending upwards in all crowded city centers, and if city and state leaders don't start thinking about creative solutions like robot deliveries, we can expect even worse traffic jams," says Paul Mackie, director of a transportation policy research center in Arlington.

    A study by this center found 73 percent of delivery vehicles in Arlington were parked outside of authorized areas, often blocking bike lanes and crosswalks. By moving the last step of deliveries from the road to the sidewalk, cities could reduce traffic jams and solve the parking problem entirely, Mackie says.

    Companies such as Amazon are not developing this delivery technology simply to clear up urban traffic. Self-driving vehicles and sidewalk robots could cut down last-mile delivery costs in cities by as much as 40 percent, according to a 2018 report by a consultancy firm. A delivery robot can cost thousands of dollars to manufacture, and most currently require human management and conservation. But in the long run companies that use autonomous delivery vehicles in the next several years could end up saving billions of dollars, the report stated.