Today some people call Amsterdam the "City of Bicycles" because it is a city which is flat and convenient（方便）for bicycles.

    In the 1960s, a group of cycling fans1an idea . They believed that it would be better for everybody if only bicycles were allowed in the city centre. They were2that this would help to save energy, reduce pollution and provide free public transport. The group painted hundreds of bicycles3and placed them in public places around Amsterdam for people to use.4was allowed to take them and use them for short journeys, whether he was a local or a foreigner, Wherever someone finished a journey, they would5the bike there for someone else to use. The problem was that it didn't work-thieves took all the bicycles6 weeks!

    7,more than thirty years later, the "white bike" is back in town-this time with a computer chip(芯片)to8 its every move! To take a bicycle, you have to put a special card inside. The new "White bike" is not white any more but is an unusual9with bright colours. The bikes are parked at special parking places and people who want to use them have to take them to another place that has enough room.

    There is already less traffic in central Amsterdam, 10 both locals and tourists have been using the white bikes. Thanks to the good ideas of lots of people, like the cycling fans in the 1960s, many people around the world have been enjoying city centre streets without cars for many years.

    If you do not use your arms or your legs for some time, they will become weak; when you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory (记忆) works in the same way. When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory is poor, he really means that he does not give it enough chance (机会) to become strong.

    If a friend says that his arms and legs are weak, we know that it is his own fault (过错). But if he tells to us that he has a poor memory, many of us think that his parents may be to blame (责备), and few of us know that it is just his own fault. Have you ever found that some people can't read or write but usually they have better memories? This is because they cannot read or write, they have to remember the things. Since they cannot write them down in a small notebook, they have to remember days, names, songs and stories. Therefore, their memory is being exercised the whole time.

    So if you want to have a good memory, learn from the people：practise remembering things as other people do.

    The Legendary Berlnuda Triangle (百慕大三角): A Mystery No More

    For years, people have believed that an area of the Atlantic Ocean between Bermuda, Puerto Rico and Florida, USA was a dangerous place. They thought planes and boats passing through here were likely to disappear. By 1964, a writer had called the area the "'Bermuda Triangle". The name stuck, and so did the mystery.

    In 1945, five US Navy planes, called Flight 19 took off from Florida and never came back. After they disappeared into the Bermuda Triangle, different ideas had begun to spread that the area was a dangerous place. Even before this famous flight, several ships had disappeared in these waters. People had many different ideas about why this appended. Some people even believed that a huge octopus (章鱼) was responsible!

    However, scientists believe that weather is part of the problem. Unusually shaped clouds above the area create strong winds that go down into the water, creating huge tsunami (海啸) waves that can take down boats or low-flying planes. And many researchers believe that there's no mystery, at all Ship goes down and plane accidents happen all over the world. It just seems to happen more in the Bermuda Triangle because there's more traffic.

    The Bermuda Triangle is also one of the deepest areas of the Atlantic, with some areas being 8 km (5 mi.) deep. So, remains are hard to find which makes the disappearances seem even more mysterious. In 2011, the Flight 19 planes were found, showing that they didn't completely disappear. But no matter how much evidence（证据） there is that the Bermuda Triangle is no more dangerous than any other part of the ocean, many still believe that you mustn't go there.

    Hello, my name is Clock. I have a round face. I have three hands. One hand is short, and two hands are long. I don't have arms, but my hands can turn(转动)round and round. I don't have legs, but I can walk(走路). I don't have a mouth, but I can speak. I can wake you up(叫醒). Do you know me? Who am I? Please guess!

    Is there intelligent (有智力的) life on other planets? For years, scientists said "no" or "we don't know". But today this is changing. Seth Shostak and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists (存在) somewhere in the universe. They also think we will soon contact these beings (人；生物).

    Why do Shostak and Barnett think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. "This is long enough for other planets to have intelligent life," say Shostak and Barnett. The second reason is size—the universe is huge. "Tools like the Hubble Telescope (哈勃望远镜) have shown that there are at least 100 billion galaxies," says Shostak. "And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be similar to Earth."

    In the past, it was hard to look for signs of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to discover smaller planets. These planets might have intelligent life.

    Have beings from space already visited Earth? "Probably not," says Shostak. However, intelligent beings may contact us in other way, such as radio signals (信号). In fact, they may be trying to communicate with us now, but we don't have the right tools to receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other.