It is a question that has confused parents for many years: why do children refuse to eat greens?

    Now, two American experts believe they have the answer.

    After studying dozens of babies as they played with various objects, the researchers noted that they were far more unwilling to touch plants than other things. They believe this is because evolution (生物进化) has biologically made children be wary of plants.

    Due to susceptibility (敏感性) to illness or injury in the early years of life, the body has designed an inner defence mechanism (内部保护机制) that limits a child' s contact with plants, they think. The researchers believe this is why children turn their noses up when faced with a plate of broad beans.

    The findings are published in a paper by Dr Annie E Wertz and Dr Karen Wynn, both psychologists at Yale University.

    They wrote, "Throughout human evolution... plants have been important in human's life. Yet, for all of these benefits, plants have always caused very real dangers."

    "Plants produce toxins (毒素) as defences that can be harmful, or even deadly. Some plants also produce physical defences, such as thorns（荆棘）can damage tissues (组织) and cause effects over the whole body."

    They added, "We predicted that babies may have behavioural strategies that reduce dangers caused by plants."

    To test their theory, the researchers studied how children aged eight to 18 months old reacted when presented with a variety of objects. It took much longer for children to grab plants; objects that were pretended to look like plants also caused a slow response time.

    For parents attempting to spoon some peas into the mouth of their child, this finding should come as welcome relief.

    Have you ever dreamed about a trip to the space? Seeds (种子) of some vegetables and crops are a lot luckier than you, as they have travelled to space and back.

    China is among the three countries in the world that carry out agricultural research (农业研究) in space. The others are Russia and the US.

    Since 1987, China has sent about 1, 000 species of seeds into space.

    These include green peppers, tomatoes, cucumbers (黄瓜), carrots, lettuce and wheat. Even on China's first manned spacecraft Shenzhou—V, there were some seeds from Taiwan.

    "Conditions in outer space such as radiation (辐射) and low gravity can cause big changes in the seeds," said Chinese researcher Jin Xing.

    But not all seeds are better after going to space. After returning to the Earth, the best seeds are selected. These seeds produce (生产) much more and also grow faster than normal (正常的) seeds

    If you're ever apart from your children, a new study says just talking on the phone will help just as much as a hug(拥抱).

    If you're a parent who spends long hours on the job, you probably feel sorry for spending so much time away from your kids. But the results of a new study show that a mother's voice alone can be just as comforting to an anxious child as physical contact(接触).

    In an experiment, researchers from the University of Wisconsin Madison asked a group of girls between the ages of 7 and 12 to solve math problems in front of judges—a stressful situation for anyone. Before the girls were set to give their answers, the researchers measured their levels of two hormones(荷尔蒙): cortisol, which goes up during stressful periods, and oxytocin, the "love" hormone, which goes down at the same time.

    After the girls finished the problems, some of them got to meet up with their mothers right away. The moms came in and hugged the girls. Another group of the girls didn't see their mothers, but received phone calls from them, in which their mothers told them how well they'd done. The final group had no contact with their mothers, but instead watched an animal movie, March of the Penguins.

    Finally, the girls' hormone levels were measured again. Although the movie was interesting, it did nothing to reduce the children's anxiety—but, surprisingly, both the physical contact and phone calls from their mothers had the same effect on reducing the girls' stress levels.

    So, no matter how old you are, if you're feeling stressed about something in your life, a phone call to Mom might be just the key to help you feel better.

    Cars make our lives more convenient. But they can also be a problem. For example, fossil fuel(化石燃料) cars mainly cause air pollution.

    To improve the environment, many countries are developing electric vehicles(EVs，电动车). Among them, China is taking a leading role and has created the world's largest EV market.

    Last year, over 40 percent of the 753，000 EVs sold in the world were sold in China, more than twice as large as the number sold in the United States.

    "Filling up a fossil fuel car with gas(汽油) is more expensive than charging(充电) an electric car, " said Wu Hao, who bought an electric car this year.

    However, there are still some problems. It can be hard to find charging piles(充电桩) and the cars can't go far before needing to be recharged.

    Some of these problems are being solved. In 2014, China had 31，000 charging piles. Now China has the world's largest EV charging network, with more than 167，000 charging piles in total.

    Developing EVs is one of many efforts that China has made to cut down pressure on its environment after the government promised to stop increases in carbon dioxide emissions(二氧化碳排放量) by 2030.

    "As China goes, so will the world's car industry，" the Wall Street Journal said. China has taken a leading role in the world's electric vehicle industry.