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.

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Books                                  Contents
Leo the Snow Leopard By Craig Hatkoff	It was written by the best story-teller. The  story is about Leo, a young snow leopard(雪豹) that was helped by a kind man in the snowy mountains in Pakistan. Snow leopards are in danger. Leo was just two months old when he was found and he could not live in the wild on his  own.
Where Do Recyclable Materials Go By Sabbithry Persad	Tiana has been learning about recycling at  school. But after her dog, Bubbles, gets lost chasing after a recycling truck, she decides to learn  a lot more about recycling! Following Tiana, readers will learn how to take care of the environment.
The Scrap Kins Build By Brian Yanish	Meet the Scrap Kins. They are friendly monsters. In the book, they'll show you how to turn rubbish into some pretty cool things. Readers will learn how to make toy planes from plates, bags, old clothes and more. You know what they say: One person's rubbish is another person's love.
Explore( 探索) Life Cycles! By Kathleen M. Reilly	Do you know the largest seed( 种子)in the world or an egg can weigh up to 4 pounds? You'll learn about all of these things and more with the latest book in the Explore Your World series( 系列). The books give readers a good look into the life cycles of plants and animals on the Earth.

    Want to be an astronaut?Then“study hard，stay healthy and have perseverance”!

    This is what Chinese astronauts Fei Junlong and Nie Haisheng said in Hong Kong．Fei，Nie and leading engineers of Shenzhou VI visited Hong Kong from November 27 to 30，2010．

    They talked with primary，secondary and college students．Kids were interested in the astronauts' space lives．They asked questions like “Did you see the Great Wall from space?”Fei and Nie said they didn't see the Great Wall．But they felt excited when they passed over China，including Taiwan．The Taiwan Island looks very beautiful，like jade．

    Young people wanted to know how the astronauts developed(发展)their careers(职业)．“How did you decide to be astronauts when China's space industry is still at the beginning?”spoke a young woman．The astronauts said it was because of their love of flight and the need of the nation．They said their love of flight could be seen from their children's names．Nie's daughter is named Nie Tianxiang，which means“flying up high”．Fei's son is called“Fei Di”，which sounds like“Feidie”，meaning UFO．

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    Saving the Earth shouldn't be so difficult，if we can do the following．

    First，we should take our time ． There is no need to hurry．We can walk or ride a bike to work．

    Second，we should smell the Each．Open the windows．Turn off the air-conditioner, and at the same time，save the energy．

    Third，we should enjoy cooking at home and having meals on our dinner table．So we can use our own bowls and chopsticks，not the plastic ones．

    Fourth，we should spend our weekends and holidays in the park playing games and just riding a bike around.

    Fifth，we should learn how to use old things well in the house，in the garden，or in the kitchen．

    Lastly, no one really has a mountain and a sea．Don't throw rubbish here and there．

    A black hole is a place in outer space with very strong gravity. Gravity is a great force(力量) that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.

    Black holes are invisible. We can't actually see them because they don't throw back light. But scientists can find them with space telescopes(望远镜)and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction(科幻)stories, although they are very real.

    A black hole forms when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass(质量), the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and "eat" them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.

    The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Laplace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole". Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.