Experiments under way in several labs aim to create beneficial types of genetically modified foods, including starchier potatoes and caffeine-free coffee beans. Genetic engineers are even trying to transfer genes from a cold-winter fish to make a frost-resistant tomato.

    A low-sugar GM strawberry now in the works might one day allow people with health problems such as diabetes (糖尿病) to enjoy the little delicious red fruits again. GM beans and grains rich in protein(蛋白质) might help people at risk of developing kwashiorkor. Kwashiorkor, a disease caused by severe lack of protein, is common in parts of the world where there are severe food shortages.

    Commenting on GM foods, Jonathon Jones, a British researcher, said: "The future benefits will be enormous（巨大的）, and the best is yet to come". To some people, GM foods are no different from unmodified foods. "A tomato is a tomato," said Brian Sansoni, an American food manufacturer.

    Critics of GM foods challenge Sansoni's opinion. They worry about the harm that GM crops might do to people, other animals, and plants.

    In a recent lab study conducted at Cornell University, scientists tested pollen(花粉) made by BT corn, which makes up one-fourth of the U.S. corn crop. The scientist dropped the pollen onto milkweed, a plant that is the only known food source of a butterfly caterpillar(毛虫). Within four days of feeding on the leaves, almost half of a test group of caterpillars died. "This is a warning bell." said Cornell researcher Linda Raynor.

    Some insects that are not killed by GM foods might find themselves made stronger. How so? The insecticides are used on the crops to kill the pests. But GM plants produce a continuous level of insecticide. Insects relying on those crops may develop resistance to the plants and they may also develop a resistance to the insecticide.

    At the forum on GM food held last year in Canada. GM crops that have been made resistant to the herbicide might crossbreed with wild plants, creating "superweeds" that could take over whole fields.

    So where do you stand? Should GM food be banned in the United States, as they are in parts of Europe? Or do their benefits outweigh（胜过） any of the risks they might carry?

    People have been acting like people-in other words, they've been making tools, creating ceremonies, and sharing food—for a long time. That's the conclusion of a recent study from South Africa's southern coast.

    There, in a cave lying above the sea, researchers from Arizona State University have found evidence that humans were behaving in surprisingly complex ways as early as 164,000 years ago. Our species. Homo sapiens, appeared an estimated 200,000 years ago.

    The cave held three important evidences about the behavior of these Stone Age people.

    First, the researchers found the remains of all kinds of shellfish. The people who lived in the cave probably collected these creatures from rocky shores and tide pools and brought them to the cave to eat.

    The researchers consider the early Africans move to the South African coast between 195,000 and 130,000 years ago. Around that time, the climate inland turned relatively cold and dry. Therefore, there were fewer plants and animals to eat away from the coast.

    When these ancient people moved to the coast, they probably experienced a major cultural shift, the researchers suspect. That's because observations of modem hunter-gatherer societies suggest that men are more likely to hunt for big animals when people live inland. On the coast, women play a more important role in providing food by gathering plants and shellfish.

    As for the second clue, the researchers unearthed 57 pieces of reddish pigment (颜料). The researchers think that the cave habitants used the paint for coloring their bodies or for other ceremonies. Symbolic behavior is a clearly human feature.

    Finally, the search discovered over 1,800 stone tools, including well crafted blades (刀片). These blades came in various sizes. The smallest were just less than a half inch wide. Ancient people may have attached these blades to the end of a stick to make spears or other tools.

    On November 24, 1868, Scott Joplin was born in Texas. He became famous as a ragtime (拉格泰姆音乐) composer and piano player. Ragtime music was an early form of jazz. This music has a lively beat and was developed from the music of African Americans.

    Ragtime became popular in the early 1890s, and the music was played on the piano. The piano player usually made up a melody, then changed it a little bit every time he played. Scott Joplin was very good at composing, or making up music and playing the piano. When he was growing up, Joplin's home was filled with music. Still, Joplin's father did not want him to be a musician. When he was about 14 years old, Joplin left home to travel and start a life of his own. He traveled all over the Midwest playing the piano and composing music. Sometimes he played with music groups. Other times he sang by himself in noisy saloons and bars. In 1899, Joplin wrote Maple Leaf Rag, a ragtime song that became a big hit and earned Joplin the title of The King of Ragtime. In all, he wrote more than 500 songs. Joplin's biggest dream was to compose a ragtime opera. Finally, after 10 years, Joplin completed a ragtime opera which he called Treemonisha. This opera was about a young black woman who became a leader of her people. She tried to help her people gain their freedom and their rights.

    1916, Joplin became very sick. He had a disease that made him forget things and become easily afraid of things. In 1917, he was put in the hospital. He finally died there on April 1, 1917. Scott Joplin's music became popular again in the early 1970s when it was used in a movie called The Sting.

    Do you find it difficult to put down your mobile phone?

    If yes, you're not alone. These days, many people suffer from the stress of FOMO (fear of missing out). They reach for their mobile phones when they wake up in the morning, and for the rest of the day, they constantly scroll down (向下滚动) the timelines of their social media apps to get the latest updates.

    Despite the convenience smartphones bring, many people struggle with their digital habits.

    As Sameer Samat, US tech Company Google's vice president of product management, said in his speech at the 2018 Google I/O developer conference on May 8, 70 percent of people don't want to spend so much time on their phones.

    This is why during the conference Google introduced an app called Dashboard for the new version (版本) of its Android operating system. This new app includes well-being functions that aim to help users manage the time they spend on their digital devices.

    It all starts with a bird's-eye view. Dashboard allows users to look at all the details of their phone habits. For example, a user can see how many times they've unlocked their phone and how many times they've checked their social media apps, as well as how much time they spend on each app every day.

    Once the users see this information, they'll be able to make some changes. With the App Timer function, users can set a time limit for how long they can use each app for every day. After they've hit the limit, they won't be able to launch the app until the next day.

    But even if users become more mindful of their usage, they're still likely to be drawn in by notifications (通知). This is where the Shush feature comes in. It automatically (自动地) silences incoming calls and notifications when a user puts their phone face down.

    If people truly want to make full use of their free time instead of losing hours using their smart phones, these new functions are just one way of doing that.

After all, who needs to use an app to stop you from using other apps when the easiest answer would be just to use your willpower?

    It was late one evening. I can't remember what it was about, but my dad and I had a very big argument when my mom was away. We both said things we didn't mean, and in the end I said, "I'm leaving." And he said, "Good. The sooner, the better."

    I threw a few things in a suitcase and closed the door angrily behind me, not knowing where I was going. After walking aimlessly for about 20 minutes, I stopped at a local supermarket. Then my phone rang. It was my mom calling. She said, "Hey, Mary. Where are you？Dad is worried about you."

    "How can he worry about me？I've been away for nearly half an hour, but he didn't call," I said with annoyance(气恼). My anger returned and I remembered all the hateful things he'd shouted to me. "Listen, Mom. You can tell Dad that I'm fine. I'll call you tomorrow," I said and hung up.

    I walked around the store, trying to get my thoughts together. By the time I paid for my purchases, it had been much later than I used to be out alone. When I left the supermarket, a large piece of white paper was in front of me. On the piece of white paper were these words: "Please come home! I miss you and I'm worried about you！"

    Then a car pulled up beside me. Hanging out of the window was my dad. Beside him, smiling gently, sat my mom. And that's when I started laughing. I laughed so hard that I cried. Despite my best efforts to run away from home, my father finally managed to track me down. I couldn't leave now, not with him sitting there with caring eyes.

You've probably heard it a dozen times by now. But here it goes again: Sleep is important. Your mental health and immune (免疫时)system are connected to your sleeping habits. So are your grades, a new study finds. Sleep accounts for nearly one-fourth of the difference among students' grades in a class. So even if you spend hours studying for a test but get too little sleep, you might still do poorly.

Typically, people's sleep schedules are messy and can not be known in advance. Professor Jeffrey Grossman of Massachusetts Institute of Technology in Cambridge wanted to see if sleep links to people's learning performance even when a study was done with people who kept such true-to-life schedules at home. So he turned to Fitbits, which can check how long people sleep and how frequently they wake up. And the researchers looked for 100 students. They focused on these students' sleep patterns in the days and weeks before exams and then compared them to these students' test scores.

"How much time a person sleeps the night. before an exam doesn't affect that person's grade," Grossman says. "A student who sleeps 7 hours every night will do better than a student who sleeps 7.5 hours one night and 6.5 hours another night."

"It's important for people to know that if their Fitbits tell them that they have terrible sleep, that may not actually be so," Michael Scullin, a sleep scientist at Baylor University says. Grossman also raises this point. Fitbit, Inc. makes this advanced tool. But it doesn't share how its tool works. This leaves a question about whether the tool is really correct when checking a student's sleep. Even so, Scullin emphasizes that there are enough data supporting ties between sleep and how well someone performs.

"Students need more sleep and less late evening use of phones and other screens. Even with after-school activities and schoolwork, they need to get enough sleep," Grossman says.