When children start kindergarten, evident gaps in science knowledge already exist between Whites and minorities and between youngsters from upper-income and low-income families. And they often deepen into significant achievement gaps by the end of eighth grade if they are not dealt with during elementary school.

    The findings suggest that, in order for the United States to maintain(维持) long-term scientific and economic competitiveness in the world, policymakers need to renew efforts to ensure access(n.使用或见到的机会，权利) to high-quality, early learning experiences in childcare settings, preschools and elementary schools.

    The researchers' study tracked 7,757 children from their start in kindergarten to the end of eighth grade. Researchers found that, among kindergarteners with low levels of general knowledge, 62 percent were struggling in science by the time they reached third grade and 54 percent were struggling in that subject in eighth grade. And general knowledge gaps between minorities and Whites were already large at the time when students began kindergarten.

    “Children growing up in low-income families typically experience comparatively fewer early opportunities to learn about the natural and social sciences,” the authors wrote. “Their parents often have lower educational levels and therefore less science knowledge themselves as well as fewer resources available to direct the children's academic growth. Children raised in poverty often attend poorly resourced schools that futher limit their academic opportunities.”

    Morgan said that, within families, parents who regularly talk and interact with toddlers(学步的儿童) can point out and explain physical, natural and social events occurring around them daily. This might help youngsters learn facts and concepts that will prepare them to take better advantage of science instruction they receive during elementary and middle school.

    Looking good can matter a lot when you are a teenager. Of course the budget(财政） matters a lot, too. Luckily, fashion trends (流行趋势) in the UK mean that getting the right image doesn't have to cost the earth. Here's a quick guide to which looks are hot this year.

    For girls, the 70s are back. Wide-legged jeans, platform shoes and skirts that reach the feet are again in fashion among UK teens, topped off with colored, shining eyeshadow. Girls can have fun mixing and matching bright shades. Colors like pink, orange and light yellow-green are all perfectly fit. Shorts and mini-skirts are still popular in cold weather. By wearing a pair of tights underneath ( 在..底下), girls can stay warm as well as fashionable in the winter.

    How about boys? To look lively, fans of skateboards and snowboards can dress in skinny jeans accompanied by a T-shirt topped off with a baseball cap or a woolen hat. Music is often an inspiration for fashion, and hip-hop music fans like to dress in baggy jeans, T-shirts, baseball caps and sneakers. For those who can afford it, designer clothing is a must, especially if the logo is showing.

    LONDON-A British judge on Thursday sentenced a businessman who sold fake(假冒的) bomb detectors（探测器） to 10 years in prison, saying the man hadn't cared about potentially deadly consequences.

    It is believed that James McCormick got about $77.8 million from the sales of his detectors-which were based on a kind of golf ball finder--to countries including Iraq, Belgium and Saudi Arabia.

    McCormick, 57, was convicted(判罪) of cheats last month and sentenced Thursday at the Old Bailey court in London.

    “Your cheating conduct in selling a great amount of useless equipment simply for huge profit promoted a false sense of security and in all probability materially contributed to causing death and injury to innocent people,” Judge Richard Hone told McCormick. “you have neither regret, nor shame, nor any sense of guilt.”

    The detectors, sold for up to $42,000 each, were said to be able to find such dangerous objects as bombs under water and from the air. But in fact they “lacked any grounding in science” and were of no use.

    McCormick had told the court that he sold his detectors to the police in Kenya, the prison service in Hong Kong, the army in Egypt and the border control in Thailand.

    “I never had any bad results from customers,” he said

    As my dad unwrapped（打开）the new bicycle helmet（头盔）that I got him for his birthday, I realized that a number of people ride their bicycles every day without the protection of a helmet.

      Due to cold winters across the country, riding has become increasingly dangerous as many roads have holes and are torn-up（磨损的）. Not everyone realizes that there are laws requiring the wearing of helmets in many places.

    Where I live, there has been a law in place since October 1, 1992 stating that cyclists of all ages are required to wear helmets. Unfortunately, accidents can happen to the best of riders. My dad has been a cyclist for many years, and he often rides around my county and to Rockland Lake State Park.

    One afternoon, as he was just entering the park, he lost control of his bicycle and flew off and landed on a nearby patch of grass, breaking his helmet into pieces and losing consciousness（知觉）. When he was just awakening, a lovely couple found him and brought him back to our house, where he attempted to recall the events leading up to his fall. Later that day, a CAT scan showed that he had a concussion (脑震荡). That evening, while my dad was showing me the pieces of his broken helmet, we both came to a shocking realization.

    If he had not worn his helmet, he probably would have cracked his skull and perhaps died. Today, when my dad and I go out cycling, the wearing of our helmets is not even a question. Regardless of age, everyone should wear a helmet whenever they get on a bicycle.

    All over the world people enjoy sports, Sports help to keep people healthy and happy, and to live longer.

    Many people like to watch others play games. They buy tickets or turn on their TVs to watch the games. Often they get very excited when "their" player or team wins.

    Some sports are so interesting that people everywhere go in for(参加) them. Football, for example, has spread(展开)around the world. Swimming is popular in all countries near the sea or in those with many rivers. What fun it is to jump into a pool or lake, whether in China, Egypt or Italy! And think of people in cold countries. Think how many love to skate or ski (滑雪) in Japan, Norway or Canada.

    Some sports or games go back thousands of years, like running or jumping. Chinese wushu, for example, has a very long history. But basketball and volleyball are rather new. Neither one is a hundred years old yet. People are inventing new sports or games all the time. Water-skiing is one of the newest in the family of sports.

    People from different countries may not be able to understand each other, but after a game together they often become good friends. Sports help to train(培养,训练) a person's character(性格,品格). One learns to fight hard but fight fair, to win without pride and to lose with grace(胜不骄，败不馁).

    People have grown taller over the last century, with South Korean women shooting up by more than 20cm on average, and Iranian men gaining 16.5cm. A global study looked at the average height of 18-year-olds in 200 countries 1914 and 2014. The results show that while Swedes were the tallest people in the world in 1914, Dutch men have risen from l2th place to claim top spot with an average height of 182.5cm. Larvian women, meanwhile, rose from 28th place in 1914 to become the tallest in the world a century later, with an average height of 169.8cm. James Bentham, a co-author of the research says the global trend is likely but once you average over whole populations, genetics plays a less key role," he added.

    But while height has increased around the world, the trend in many countries of north and sub-Saharan Africa causes concern, says Elio Riboli of Imperial College. While height increased in Uganda and Niger during the early 20th century, the trend has reversed in recent years, with height decreasing among 18-year-olds.

    "One reason for these decreases in height is the economic situation in the 1980s," said Professor Alexander. The nutritional and health problems that followed the policy of structural adjustment, he says, led to many children and teenagers failing to reach their full potential in terms of height.

    Bentham believes the global trend of increasing height has important implications. "How tall we are now is strongly influenced by the environment we grew up in," he said. "If we give children the best possible start in life now, they will be healthier and more productive for decades to come."