Many animals hide to stay alive. They hide in many ways. Some animals hide in leaves; some animals hide in snow. Usually their colors or shapes help protect them. It's hard to see an Arctic bear in snow. Its white fur helps protect it. Chameleons(变色龙) can hide by changing colors. Their skin turns the same color as what is around them. Some chameleons can change colors in five minutes.

    Many animals try to look bigger than they are to stay alive. Some animals can make other animals think they are very big. If they look very big, animals that are looking for food will run away. Bears can walk on two legs. They look very, very scary. Some animals will run away from them.

Many animals try to stay around other animals. This helps them stay alive. Zebras stay close together so that they can help each other look out of danger. Seeing many stripes at once can also confuse animals that want to eat them. Some birds stay in a circle, each toward a different direction. In this way they can also help each other stay alive by looking around for animals that many want to eat one of them.

    Height is just one of the thousands of features your genes decide. In fact, because you have two parents, your genes provide you a height that usually lands somewhere between the height of each parent. If both your parents are tall, then most probably you will be tall, too, but if you have questions about how tall you're going to be, ask your doctor if he or she can help you find it out.

    But genes don't decide everything. For example, eating an unhealthy diet can keep you from growing to your full potential(潜力). Getting plenty of sleep and enough exercise will help you grow to the expected height.

    No doubt you're wondering how fast you should grow. It depends. There's no perfect or right answer. Generally speaking, kids grow about 2 inches (6 centimeters) a year between age 3 and the time when they start puberty (when your body starts changing and becoming more grown up).

    Your doctor will know how your growth has been going over the years. Two centimeters here and 2 inches there are not nearly as important as the height you're at now, how you've been growing up to this point, and what other changes your body may be going through.

    Don't be scared if you seem to have grown a lot in a very short time. Everyone has a growth spurt（高峰）during____The age for starting puberty is about 10 for girls and about 11 for boys. But it can be earlier or later —between 7 and 13 for girls and 9 and 15 for boys.

    You'll usually begin to notice that you're growing faster about a year or so after your body starts to show the first changes of puberty.

    Most of us know that Ikea is the world's biggest furniture company. However, did you know that it's also a pioneer in environmental protection?

    Ikea says it's working hard to improve the environment. The company has made huge efforts to cut the carbon emissions(碳排放)of its suppliers(供应商).Over the past five years, Ikea has helped its suppliers become 18 percent more energy-efficient. It managed to do so by bringing its suppliers together. The one that produces the least carbon emissions will be praised.

    Ikea has also invested(投资)heavily in clean energy. The company now operates more than 300 wind turbines(叶轮机)around the world. It has also set up nearly 750,000 solar panels(太阳能嵌板)on the roof of its stores. As a result, Ikea can produce 71 percent of the energy it uses, which are all from clean sources. In some countries，such a} Denmark and Finland，the company produces as much energy as it uses.

    Ikea has been buying forests as well. It owns nearly 750 square kilometers of forest.

    Last but not least, Ikea has tried changing customers' behavior(行为).It does so by improving product designs. In 2015, Ikea changed all of its lighting products into LED. This change alone, it says, has saved lots of electricity.

    How do you pay for your meals at a fast food restaurant? With change(零钱)? Nowadays we have We Chat wallet and Alipay.

    I use my tap-and-go card(感应式信用卡). I don't even need to enter my PIN number(SIM卡密码)or a signature(签名)to pay money. It's quicker and everybody in the queue(队)is happy.

    Contactless payments(非接触式支付)are more and more popular, but the safety (安全性)still needs improving(改善). And people shouldn't pay too much at a time-in the UK it's ￡30. If you use the card a few times, you will need your PIN number.

    Some things, such as your clothes, have been combined with electric technology(与电子技术联系起来). Kenneth Cukier, the writer of the book Big Data, says, "You can take any card and put it in a coat. When you make a payment, just wave your arm in front of the terminal(终端)." This is for people who don't want to take their card out of their pocket, or use their phone or watch.

    Good, isn't it?

    So spending money is becoming easier at the time. And people are buying more and more things. But making money still needs the hard work.

    Back to work then!

    Some people claim they" never forget a face". But what does that saying mean? Is there really no limit to the number of faces a person can remember? A new study at the University of York in England has found that, on average, people can remember as many as 5,000 faces.

    The study is the first time that scientists have been able to put a number to the abilities of humans to recognize faces. The research team tested people on how many faces they could remember from their personal lives and in the media. They also tested them to see how many famous faces they recognized. Rob Jenkins works in the psychology department at the University of York. He said the researchers' study centered on the number of faces people actually know. He said the researchers were not able to discover whether there is a limit on how many faces the brain can handle.

    In the study, people spent one hour writing down as many faces from their personal lives as possible. At first, they found it easy to come up with many faces. But by the end of the hour, they found it harder to think of new ones. Their change in speed let the researchers estimate when they would have run out of faces completely.

    The results showed that these people knew between 1,000 and 10,000 faces. Jenkins explained that some people may have a natural ability for remembering faces." There are differences in how much attention people pay to faces and how well they process the information," he said. Jenkins also said it could be because of different social environments. Some people may have grown up in more populated places. Therefore, they may have had more social contact throughout their lives.

    The people in the study included 25 men and women between 18 and 61 years old. Researchers think age may be an interesting area for further research. "It would be interesting to see whether there is a peak age for the number of faces we know", Jenkins said. He said it is possible that we gather more faces throughout our lifetime. But, he added, there also may be an age at which we start to find it harder to remember all of those faces.

    The study suggests our facial recognition abilities enable us to deal with the many different faces we see on the screens, as well as those we know, like family and friends. Today, facial recognition technology is used in many ways, including by law enforcement agencies to prevent crime and violence. Governments use it to keep secret areas secure and, in extreme cases, control populations. .Even Facebook uses facial recognition. For example, when you "tag" or name a friend, Facebook technology may recognize the person's face from a different picture you had shared before.