If you are riding a bike in foreign countries, you need to know what these traffic signs mean.

1		This sign means “walk”, you can cross the street along with other people.
2		This sign is the “don't walk” sign. It means you should stop to wait for a while until the sign of “walk” is showing.
3		This sign means that there is a bike lane. If you see such a sign, you must use the bike lane.
4		Car drivers and bike riders must come to a complete stop at “STOP” signs.
5		This sign means you are coming to a zebra crossing. You must slow down to allow people in the zebra crossing to cross the street.
6		This sign means parts of the road are rough. Be careful! Rough roads make you fall off your bike.

    E-waste is fast becoming a serious problem around the world. This report will examine this problem and provide some possible ways to solve it.

We live in a society that is producing and using electronics(电子产品) all the time. It is often cheaper to buy new products than to repair old ones. Also, through clever advertising, companies always encourage people to change their old TVs, mobile phones and computers for the latest models. E-waste is created when we throw away old ones. In the EU alone, about 8,700,000 tons of e-waste is produced each year. Sadly, just over 1,000,000 tons is recycled.

    Burying(填埋) e-waste or burning it cause serious problems for the environment. Electronics have dangerous things in them. These things can then get into the ground or pollute the air when they are burnt.

    In recent years,   ▲  . However, their plans are not always managed properly. Sometimes electronics are just sent to poor countries such as Ghana. Here they are often burnt in public areas, which is very bad for people's health. Setting up recycling centers is a good way to solve this problem. E-cycling centers could recycle the parts that can be reused and deal with the rest properly.

    Another way is to make producers responsible(负责任) for their used products. This means that producers must take back old products which are no longer wanted. They should then make sure they are properly recycled or reused.

    As for us, we should try to cut down on e-waste. Change electronics only when we have to. And don't buy a product just to have the latest model.

    E-waste is a serious problem in the modern world. Both producers and users must take actions and try to keep it to the smallest amount.

    Have you ever heard of e-waste, which can be produced every day? How do you deal with your computers, MP4 players and mobile phones when they're broken or you want a new one?

    Most people just throw them away. With the development of electric industry, e-waste pollution has become a serious problem. According to the United Nations, in 2014, people around the world produced 41.8 million tons of e-waste and only recycled 6.5 million tons. The US was the biggest waster, producing 7.1 million tons. China came second, with 6 million tons.

    It's important to pay attention to e-waste. It can either be valuable or harmful, depending on how we deal with it. E-waste is a valuable urban mine. The value of the metals, like gold and silver in the waste around the world, is amazing. And the metals can be reused. But if people throw them away, the toxic chemicals can get into the earth or air, effecting the environment and people's health.

    Apple, for example, now recycle people's used products in China when they are buying new ones. The company will test and repair the used ones and sell them at lower prices. To help reduce e-waste, we can also take computers and phones to see if companies offer recycling programs.

    What is the first thing you want to do when you see someone yawn(打哈欠)? You want to yawn, too! Yawning is contagious.

    Scientists have found that all people yawn. Babies start to yawn even before they are born. The earliest yawn takes place when a baby is still inside its mother. When young children are about one year old, they start to yawn when they see others yawning. That's why scientists seem to think yawning is contagious.

    It's no secret that yawning is contagious, but why do we yawn? Well, scientists are not really sure.

    Some think we yawn because we feel bored. Recently scientists studied two groups of students between the ages of 17 and 19. One group watched music videos, and the other watched a boring color test. Scientists compared the numbers of their yawns and found that the color test group yawned more times than the video group.

    Another reason about yawning has to do with breathing. Some scientists believe that when we are bored or tired, we breathe more slowly. As our breathing slows down, we cannot get rid of(去除) enough carbon dioxide (CO₂) in our bodies. When there is too much carbon dioxide, our bodies will tell the brains (大脑) to breathe deeply. The result is a big yawn.                                                           

    In 2007, scientists suggested a new reason. They said that the reason people yawned was to cool down their brains. These scientists found that people who were warmer than others yawned more often.

    Scientists are still trying to find out why yawning happens and why it is so contagious. But they are only sure that when one person yawns, almost everyone else nearby wants to yawn, too.

Why Do People Blink (眨眼) Their Eyes?

    People blink their eyes tens of thousands of times every day. Scientists have long believed blinking was an involuntary movement and served mainly to keep the eyeballs wet. But a new study suggests it has a more important purpose.

    An international team of scientists from the University of California at Berkeley studied the blinking of human eyelids. The journal Current Biology published their findings. The team said they found that blinking "repositions our eyeballs so we can stay focused" on what we are seeing. They said that when we blink our eyelids, the eyes roll back into their sockets—the bony area that surrounds and protects the eyes. However, the researchers found the eyes don't always return to the same position (位置). They said this causes the brain to tell the eye muscles (肌肉) to reorganize our eyesight.

    Gerrit Maus is the lead writer of the report. He serves as an assistant professor of psychology at Nanyang Technological University in Singapore. Maus said, "Our eye muscles are quite sluggish (迟缓的) and imprecise (不精确的), so the brain needs to constantly adapt (改编) its motor signals to make sure our eyes are pointing where they should be. Our findings suggested that the brain measures the difference in what we see before and after a blink, and orders the eye muscles to make the needed corrections." The researchers said that without such corrections our surroundings would appear unclear and even jumpy. They said the movement acts "like a steadicam (摄影稳定器) of the mind."

    The researchers said they asked volunteers to sit in a dark room while storing at a small dot on a flat surface. They used special cameras to follow the volunteer's blinks and eye movements. After each blink, the dot was moved one centimeter to the right. The volunteers did not notice this, but the brain did. It followed the movement and directed the eye muscles to refocus on the dot. After the dot was moved in this way 30 times, the volunteers' eyes changed their focus to the place where they predicted it would be.

    Professor Maus said. "Even though the volunteers did not consciously register that the dot had moved, their brains did, and adjusted (调整)with the corrective eye movements. These findings add to our understanding of how the brain constantly adapts to (适应) changes directing our eye muscles to correct for errors in our bodies' own hardware."