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    Newborns begin to develop language skills long before they begin speaking. And, compared to adults, they develop these skills more quickly. People have a hard time learning new languages as they grow older, but babies have the ability to learn any language easily.

    For a long time, scientists have tried to explain how such young children can learn the complicated grammatical rules and sounds of a language. Now, researchers are getting a better idea of what's happening in the brains of the tiniest language learners. This new information might help kids with learning problems as well as adults who want to learn new languages. It might even help scientists who are trying to design computers that can communicate like people do.

    Most babies go “ma ma” by 6 months of age, and most children speak in full sentences by age 3. For many years, scientists have wondered how the brains of young children figure out how to communicate using language. With help from new technologies, scientists are now finding that babies begin life with the ability to learn any language. They get into contact with other people, listen to what they say and watch their movements very closely. That is why they quickly master the languages they hear most often.

    Studies show that, up to about 6 months of age, babies can recognize all the sounds that make up all the languages in the world. Starting at around 6 months old a baby's brain focuses on the most common sounds it hears. Then, children begin responding only to the sounds of the language they hear the most.

    In a similar way older babies start recognizing the patterns that make up the rules of their native language. For example, English children who are about 18 months old start to figure out that words ending in “-ing” or “-ed” are usually verbs, and that verbs are action words.

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    My folks bought their first house in the early 1940s after Dad got a better job in Marquette, Michigan. We lived just inside the city limits in what was still a rural area.

    In the spring of 1948, when I was 6 years old, my parents bought a calf (小牛) to replace our cow, which had been killed the year before. So one day we drove to a local farm and returned with a white and brown calf we named Tubby.

    We didn't own a truck, so Tubby rode home in the backseat of Dad's car with my 9-year-old brother Steve, and me. As you can imagine, the trip was a lot of fun for us kids.

    Later that summer, Mom thought it would be cute to take a picture of me sitting on Tubby's back. All went well unti1 the snap of the camera shutter sent Tubby charging off on a run, with me holding on for dear life. I lasted for about 30 feet before I hit the ground. Mom was quick enough to shoot a follow-up picture, so we had photos of me both on and off Tubby!

    When summer had passed, the day arrived for poor Tubby to fill our freezer I must have been somewhere else with my Mom on the fateful day, because I have no memory of how it happened. All I knew was that the barn was empty, and that we had plenty of meat for dinners.

    I hadn't lived on a farm like my mother, so I didn't understand that what happened to Tubby was not unusual. Livestock aren't meant to be pets, and most farm kids know and accept that truth.

    Whenever we had beef for dinner, I would tearfully, “Is this Tubby” This went on for a couple of weeks until Dad had finally had enough and declared, “No more cows!” That made me feel a little better about poor Tubby.

公安部、教育部联合下发通知，各中小学要将消防安全知识纳入教学内容。对此，某市各中小学积极开展了消防演练、知识竞答、消防运动会、主题展览等消防主题活动。开展这些消防主题活动有利于（    ）

①增强青少年的安全防范意识                ②杜绝各种侵害，保证青少年平安健康成长

③体会生命的可贵，学会珍爱生命        ④提高未成年人的自我保护能力

某物理兴趣小组的同学们为自己的房间设计了一种冬天取暖的电路模型．如图所示，只闭合开关S，灯泡L发光，发热电阻丝R₁工作；温度较低时，可再闭合S₁、S₂，由发热电阻丝改成的滑动变阻器开始工作．电源电压为24V，R₂上标有“100Ω 3A”的字样，电流表的量程为0～0.6A，电流表的量程为 0～3A，灯泡上标有“12V 3W”的字样．