Even if trees cannot walk, they are still on the move.

    In parts of the Arctic, entire forests are moving northward. Across the Arctic, temperatures are rising faster than anywhere else in the world. As that happens, the tree line that marks where forests stop and the treeless tundra(冻土地带) starts has been shifting northward. Trees growing along the tree line must protect themselves from the cold wind. To do this, plants tend to grow horizontal(水平的) branches low to the ground. The energy it takes for trees to grow this way means they don't have enough energy to make seeds.

    But as Earth's climate has been warming, trees no longer have to just grow horizontally. Many can instead grow up toward the sky. This takes less energy. And with all the leftover energy. these trees have started producing more seeds. This happens especially in places where the white spruce(白云杉) grows.

    White spruce, which is a North American tree, is quite able to produce a lot of seeds, which can move long distances in the wind. When wind-blown seeds end up on the tundra beyond the tree line, they eventually can sprout(发芽) new trees. This explains how a forest can move. Of course, the process would work only if the tundra were warm enough. But in recent years, the whole planet has been warming.

    New trees will provide shelters for some snow, keeping the sun's rays from making the white surface disappear. Instead, the trees absorb the sun's heat. This warms the surrounding air. The extra warmth encourages even more trees to produce seeds. That further boosts a forest's ability to expand. In addition, more trees will trap more snow, preventing much of it from being blown away. Snow can trap heat in the soil below, which encourages trees to grow. The recent rise of temperature has helped more trees grow. The recent rise of temperatures has helped more trees grow past the tree line. People worry about impacts on the animals that depend on frozen conditions for food and shelter.

    A good book can be satisfying. If reading is a habit you'd like to get into, there are some ways to develop it.

    Realize that reading is enjoyable if you have a good book. If you have a difficult book and you are forcing yourself through it, it will seem like a task.{#blank#}1{#/blank#}

    Set time. You should have some time during every day when you'll read for at least 5 to 10 minutes. {#blank#}2{#/blank#}For example, make it a habit to read during breakfast and lunch and even dinner if you eat alone.

    Always carry a book. {#blank#}3{#/blank#}.When I leave the house, I always make sure to have my car keys and one book at hand. The book stays with me in the car, and I take it into the office and to appointments and pretty much everywhere I go.

    {#blank#}4{#/blank#} Find a place in your home where you can sit in a comfortable chair. Don't lie down unless you're going to sleep. There should be television or computer near the chair, and no music or no noisy family members/roommates. If you don't have a place like this, create one.

    Reduce television/the Internet. If you really want to read more, try cutting back on time on TV or the Internet.{#blank#}5{#/blank#}Still, every minute you reduce of the Internet/TV, you could use for reading. This could create hours of book reading time.

A. Wherever you go, take a book with you.

B. Go to bookstores.

C. Have some good tea or coffee while you read.

D. Find a quiet place.

E. This may be difficult for some people.

F. If this happens, give up the book and find another one that you'll really love.

G. It means you will read no matter how busy you are.

    Once an old man rose early to read each morning. His grandson wanted to be just like his grandfather, so tried to emulate him every way he could.

    One day the grandson asked, “Grandpa, I try to read just like you do, but I don't understand most of it, and I forget whatever I do understand immediately I close the book. So what good is it for me to read?”

    The grandfather, who was putting coal on the fire, said, “Take this coal basket down to the river and bring me back a basket of water.”

    The boy did as told to, but the water leaked out before he could get the basket home.

    The grandfather laughed, saying, “You'll have to move a little faster.” This time he ran faster, but again the basket emptied. Out of breath, he decided it was impossible to carry water in a basket, and he went to get a bucket（桶）. But the grandfather said, “I want a basket of water instead of a bucket of water. You're just not trying hard enough.”

    The boy knew what he was trying to accomplish was impossible. However, he decided to show his grandfather a third time.

    The boy dipped the basket into the river and ran as hard as he could. With the empty basket, he gasped（喘气说）, “See Grandpa? It's useless!”

    “So you think it useless?” the old man asked. “Then look at the basket.” To his surprise, the boy found it washed clean of the dirty coal stains and now clean inside and out.

    “My child, that's what happens when you read the book. You might not understand or remember everything, but the words will change you inside and out. That is the work of reading in our lives.”

    Exercise is known to benefit people's mental health, but scientists recently discovered that too much exercise may have a negative effect on it.

    The researchers studied about 1.2 million people in the United States in 2013, 2015 and 2017. The participants, on average, experienced 3, 4 days of poor mental health each month. Those who did exercise experienced 1, 5 fewer days of poor mental health per month, compared to those who didn't exercise at all. The team found that people who exercised for 30 to 60 minutes three to five times a week had the best mental health, but those who exercised for more than three hours had worse mental health than those who didn't exercise at all.

    The scientists think that people who exercise so much may experience poorer mental health because that much exercise can be a sign of obsessive (强迫症患者) behaviors that have been associated with poor emotional and psychological outcomes. However, the only mental health disorder that the researchers looked at was depression.

    Among those who had been diagnosed with depression, people who did exercise experienced 3.75 fewer negative mental health days than those who did not, showing an ever greater difference, According to the Centers for Disease Control and Prevention. 7, 6 percent of people in the U.S. age 12 and over have depression. While all types of exercise appeared to help with mental health, cycling, gym-based exercise and team sports were the most beneficial.

    The team also looked at more specific factors, like education. People with a college education reported 17.8 percent fewer days of poor mental health than those without that level education Additionally, people in a healthy BMI (体重指数) range reported a 4 percent reduction in poor mental health days thin those whose BMIs were high. Even salary was a factor: compared to people with bower salaries, those with higher salaries experienced a 17 percent reduction in poor mental health days.

    The study showed that exercise can help with mental health, but that in some cases, limiting it may be necessary.

    Tencent announced yesterday that it will limit the daily time for youngsters to play its popular King of Glory game after parents and schools in Shanghai and other areas complained their children had become addicted to playing it.

    From tomorrow, children younger than 12 will only be allowed to play the game for a maximum(最大值) of one hour a day, and after 9 pm, they will be banned from logging into it, said Tencent. Those older than 12 will be able to play a maximum two hours a day.

    The game system will remind players the time they have been playing and young players will be forced to log out when the time is up.

    Tencent claimed these were the strictest measures in China's game industry to prevent addiction and the company expected they would ease parents' anxiety.

    The company also said it had updated its system for parents to keep tabs on their children using its games.

    Since February, parents can receive messages when children log in and spend money on the game after they connect children's game accounts with their mobile phone numbers.

    Now, parents can connect phones, tablets or computers that their children use to play games, so that they can keep an eye on the children even if they have several game accounts, Tencent said.

    Song Zhe, a father of a Shanghai high school student, welcomed the measures but was not sure if they would be sufficiently effective. "I like the system that could lock up the devices as children can register many accounts," he said, "but children are so clever that they can always think out counter measures."