It is easier to float in the ocean than it is to float in a swimming pool.Do you know why?

    Ocean water is full of salt--and salt water can hold up more weight than fresh water.See for yourself!

You will Need:

3 cups of warm water

Measuring cup(量杯)

Wide-mouthed jar

Salt

Spoon

Raw(生的)potato

You Will Do:

⒈Pour 1.5cups of warm water into the jar.

⒉Add 1/3 cup of salt.

⒊Stir(搅拌) until the salt is completely dissolved.

⒋Add another 1.5 cups of water.Pour it slowly over the back of the spoon into the jar so that the two liquids will not mix together.

⒌Gently place the potato into the jar.Do not drop it.

    What Will Happen:

    The potato will sink--but only halfway!

    Why?

    Salt water is heavier than fresh water,so it will stay on the bottom.The fresh water will remain on top.

    The potato is heavier than the fresh water,but it is lighter than the salt water.That is why the potato will sink halfway down.

    Knowing how much her own children loved presents at Christmas, Ann Sutton always tried to seek help for one or two poor families. With a social worker mother, the Sutton children had inherited her commitment to service, and knew never to take their good fortune at Christmas for granted. This year, Kinzie, her seven-year-old daughter was thrilled that Santa Claus would make a special visit to a 22-year-old mother named Ashley who worked in a factory raising her 12-month-old son by herself.

    The phone rang on Sunday. A representative from a local organization was calling to say that the aid Ann had requested for Ashley had fallen through. No Santa Claus, no presents, nothing.

    Ann saw the cheer vanish from her children's faces at the news. Without a word, Kinzie ran into her bedroom. She returned, her face set with determination. Opening up her piggy bank, she put all the coins onto the table: $3.30. Everything she had.

    “Mom,” she told Ann, “I know it's not much. But maybe this will buy a present for the baby.”

    At a breakfast meeting the next day, Ann told her coworkers about her daughter's story. To her surprise, staff members began to open their purses and empty their pockets to help Kinzie. By day's end, the story of Kinzie's gift had spread beyond Ann's office. She received a call from an unknown donor. If a seven-year-old could give everything she had, he said, he should at least match her gift 100 to 1. He contributed $300.

    On Christmas Eve, Ann drove through the pouring rain to the small trailer where the Ashleys lived. Then she began to unload the gifts from the car, handing them to Ashley one by one.

    Ashley was very moved. Reflecting on a little girl's generosity, Ashley says she'll one day be able to do something similar for someone else in need. “Kinzie could have used that money for herself, but she gave it away,” Ashley says. “She's the type of kid I'd like my son to grow up to be.”

阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。

    The Gold Coast family holidays are always great fun whether you are from Australia or from abroad. There are beautiful beaches, adventure (冒险) parks, nature parks and so much more.

    There are so many sights to see here. It is a pity to drive in a car and you'll miss a great part of it. Australia is home to many animals and birds that can only be seen when moving slowly and going into the areas where they live.

    When you are on a bicycle, you have the advantage of being able to stop whenever you want to see an interesting animal or bird that you have never seen before. It is a quieter way of transportation as well, so you might even be able to take a picture. When you are on the beach, you can breathe that clean air and view the beauty of the water and sand. It is a totally different experience from passing it in a car.

    There are many choices of hiring (租用) a bicycle to experience the Gold Coast. There are stores that will fit a bike perfectly to your size. These bikes for both adults and children are in many kinds and colors to please any taste. If you have ever wanted to try a tandem bike (双人单车), now is your chance, because they have those too.

    A bicycle hire on Gold Coast is something that everyone should try at least once. This is a wonderful chance for anyone who likes to cycle and it is also a cheap way to travel with your family.

    A team of UK researchers recently compared the performances of 120 women and 120 men in a computer test involving switching between tasks of counting and shape recognition.

    Men and women were equally capable when tasks were handled one at a time. But when the tasks were mixed up, there was a clear difference. According to the paper published in the journal BMC Psychology, both women and men slowed down and made more mistakes as the switching became more rapid. But the men were slower, taking 77 percent longer to answer, whereas women took 69 percent longer.

    To make the experiment more relevant to day-to-day life, researchers tried a second test. A group of women and men were given eight minutes to complete a series of everyday tasks, such as finding restaurants on a map, doing simple math problems, answering a phone call, or deciding how they would search for a lost key in afield. Once again, women outperformed men in the test, particularly in the key-searching task.

    “It suggests that in a stressed and complex situation women are more able to stop and think about what's going on in front of them,” researcher Keith Laws of the University of Hertfordshire, UK, told BBC News. “In contrast, men had a slight impulsiveness（冲动）, answering without giving much thought to their responses.”

    So where do women get the ability to keep organized under pressure better than men? Researchers believe that it has its roots in evolution. In early human communities, women had to keep an eye on children while cooking meals. Meanwhile, men only needed to focus on hunting.

    Did you see snow in your hometown last winter? Did you feel it was warmer than before?

“There have been 21 warm winters in China since 1986,” said scientists. They also said that in the past 100 years, as the global (全球的) temperatures went up by 0.74 ℃ , the temperature in North China has climbed 1.4 ℃ in only 50 years.

    China needs to take quick action to cut carbon dioxide (二氧化碳) emission (排放),because it's the main reason for global warming. The good news is that China has seen the importance of going green. China set the goal of cutting energy use by 20 and pollution emission by 10 in the 11th Five-Year Plan.

    Can you slow global warming? Sure! You and your family can take steps to cut the amount of carbon dioxide that is sent out into the air.

    Here are some pieces of advice to help you save the earth.

    Wear used clothes. Wearing your brother's, sister's or dad's old T-shirt means you save the energy.

    Change your light bulbs (灯泡). Use energy-saving light bulbs. And don't forget to turn off the lights when you leave a room and turn off your television and computer when they are not in use!

    Ride the bus. Taking a bus saves a lot of oil every year.

    Say no to plastic bags. The next time your parents go to the market, ask them to use baskets.

    Open a window. Don't use the air conditioner (空调), and let some fresh air in. When you have to use the conditioner, set the temperature higher in the summer and lower in the winter to save energy

    Make small changes in your daily life. Don't use paper cups, bags and boxes.

It's time for all of us to do something to save the earth.

    I often dreamed about Pisa when I was a boy. I read about the famous building called the Leaning Towers of Pisa(比萨斜塔）. But when I read the word Pisa, I was thinking of pizza. I thought this tower must be the best place to buy pizza in the world.

    Many years later, I finally saw the Leaning Tower. I knew then that it was Pisa and no pizza and that the tower got its name because it really did lean to one side. Some people want to try to fix it. They are afraid that it may fall over and they don't want it to lean over the city.

    I don't think it a good idea to try to fix it. The tower probably will not fall down. It's 600 years old. Why should anything happen to it now? And, if you ask me, I like what it looks like. It seems to say nothing is perfect. Imperfect things may be more interesting. Why is it so famous? There are many other older, more beautiful towers in Italy but Pisa tower is the most famous.