Babies born after 2017 may never need to take a driving lesson because of the development of self ­driving cars. Some scientists say that self ­driving or driverless cars(无人驾驶汽车)may hit the roads within 15 years, and it is possible that driving may become unnecessary, or more relaxing and enjoyable.

    Companies like Google, Baidu, Apple and Alibaba are working on driverless cars. But, if the tests are successful, these electric self­ driving cars could be put into use very soon. This kind of cars may change the way we live in the future. All you have to do is to type in the address!

    According to Baidu, driverless technology has the following four advantages. Firstly, driverless cars are actually safer. With driverless cars, the number of deaths caused by accidents will decrease. Secondly, driverless cars are more efficient(效率高的) than manned cars. Thirdly, driverless cars follow the traffic rules. Therefore traffic control will be easier to achieve. At last, the cost of transportation will be reduced as the labor cost becomes less.

    There are many different technologies needed to make a successful self ­driving car. The most difficult technologies of all are environmental perception(感知), behavior prediction, planning control, HD mapping, and exact GPS.

    People already know a lot about animals. However, there are still some things about animals that may surprise you. Here are some facts about animals you probably didn't know.

    Cows do have best friends and feel stressed when they are separated. Scientists have found that cows are very social animals and a cow always makes friends with other cows. When a cow is with its friends, it feels relaxed, compared with when it is alone.

    During breeding season, a male penguin(企鹅) will offer a small stone to a female penguin as a gift. If she takes it, they will become partners. When the female penguin lays an egg, she and her partner may carry it on their feet, because some penguins don't build nests(鸟巢).

    Crocodiles(鳄鱼) swallow(吞) stones. Crocodiles always swallow their food instead of eating it like other animals. They swallow stones which break the food into very small pieces in their stomachs. These stones may stay in their stomachs all their lives.

    Elephants use plants to treat pain or other illness. Scientists once found a pregnant (怀孕) elephant in Africa who ate a kind of plant which was not part of her normal food. Four days later, she gave birth to a baby elephant. The same plant was used by the local pregnant women.

    Light and shadow（影子）are friends. They usually go together. We receive light every day. At the same time, we produce shadow.

    Light cannot shine through you. Your body stops it from passing. There is a dark spot on the ground next to you. The light cannot reach the dark spot. This is your shadow.

    At noon the Sun shines over your head. Your body stops very little light from reaching the ground.

    We love light, especially sunlight. Without sunlight, life on the Earth is impossible. Most of us like to stand in the shadow of a tree in summer. But some people are afraid of their own shadow at night. They do not want to walk in a dark street. They do not want to see the shadow either. But still light and shadow usually go together.

    We know people can be nice, but what about animals?

    Scientists say that some animals are capable(有能力的)of being nice. Animals that live in groups-like foxes, chimpanzees(大猩猩), and elephants-follow rules. They have to follow rules to get along and to survive(生存). However, animals can act nicely, even when they don't have to. Here are some surprising stories about animal behavior.

    Most people usually walk away when someone is unkind to them. Marc Bekoff, a researcher at the University of Colorado, saw a female(母的)red fox do just that. The female fox was unhappy because a male(公的)fox played roughly(粗鲁地)with her. When she walked away, the male fox showed her that he wanted to play nicely. He lowered his head and rolled on his back. The female fox gave him another chance, and this time, he played more gently.

    Geza Teleki is a scientist who studies chimpanzees in Tanzania. One day, Teleki hiked far away from his campsite. He didn't have any food. Teleki wanted some fruit from a tree, but the tree was too tall. A young chimpanzee watched him curiously as he tried to get something to eat. The chimpanzee climbed the tree, picked the fruit, and gave it to him!

    An elephant in Kenya hurt his trunk(象鼻子). He needed help because he couldn't put food into his mouth. Researcher Kayhan Ostovar watched silently. He saw the hurt elephant show his sore trunk to a healthy elephant. The healthy elephant didn't need any more information. He took a bush and put it carefully into his new friend's mouth.

    Hippos(河马)and crocodiles are usually good friends. They hang out together in rivers. But Karen Paolillo, a wildlife expert in Zimbabwe, saw something surprising. One day, a crocodile tried to eat a monkey that was next to a river. A hippo ran quickly to the crocodile and chased it away. Why did the hippo attack(攻击)the crocodile? Paolillo says hippos sometimes protect other animals from crocodiles.

    Many scientists believe our love of sugar may actually be an addiction (上瘾). When we eat or drink sugary foods, the sugar enters our blood and influences parts of our brain that make us feel good. Then the good feeling goes away, leaving us wanting more. All tasty foods do this, but sugar has a particularly strong effect. In this way, it is in fact addictive, and doctors suggest we all cut down on it.

    "It seems like every time I study an illness, I find my way back to sugar," says scientist Richard Johnson. One-third of adults worldwide have high blood pressure (血压), and up to 347 million have diabetes (糖尿病). Why? "Sugar, we believe, is one of the reasons, if not the main reason," says Johnson.

    Our bodies are designed to survive on very little sugar. Early humans often had very little food, so our bodies learned to keep sugar as fat. In this way, we had energy stored for when there was no food. But today, most people have more than enough. So the very thing that once saved us may now be killing us.

    So what is the solution? It's obvious that we need to eat less sugar. The trouble is, in today's world, it's extremely difficult to avoid. From breakfast cereals to after-dinner desserts, our foods are increasingly filled with it. Some manufacturers (制造商) even use sugar to replace taste in foods that are advertised as low in fat. This may make the food appear as healthier, but large amounts of sugar are often added.

    But there are those who are fighting back against sugar. Many schools are offering more fruit instead of deserts. Other schools are building facilities for students to do exercise. The battle has not yet been lost.