请根据短文内容，简要回答下列问题.

    Tom walked into a shop. It had a sign outside: “Second-hand (旧的）clothes bought and sold.” He was carrying an old pair of trousers and asked the owner of the shop, “How much will you give me for these?” The man looked at them and then said,“Two dollars. ”

  “What?!” said Tom. “I thought they were worth at least five dollars.”

  “No,” said the man “They aren't worth a cent more than two dollars.”

  “Well,” said Toni, taking two dollars out of his pocket. “Here's your money. These trousers were hanging outside your shop. The list price (标价）of them was six dollars and a half. But I thought that was too much money, so I wanted to find out how much they were really worth.”

    Then he walked out of the shop with the pair of trousers and disappeared before the shop owner could think of anything to say.

    Do you suppose Darwin, one of the greatest scientists of all time, really did fools' (傻瓜的) experiments? Or did he do experiments that were so simple and basic (基础的) that other people just thought they were foolish?

    Sometimes, people think they already know the answer to a question or a problem．Sometimes, they really do know an answer, but without thinking it is important．

    Charles Darwin didn't just think he knew something．And, he believed all things could be important no matter how simple they seemed to be．

    Suppose you drop pieces of paper that are of exactly the same size and shape．If you drop them at the same time in the same place, they will fall in the same way．Now make one of the sheets of paper into a tight little ball and let it drop along with the other pieces．What happens? You have done an experiment that is so simple that you might think it couldn't be worth anything．

    But this simple experiment is important．It explains part of our present day understandings of physics (物理学) ideas that were worked out long ago by Galileo and Newton．And these understandings set aside some of ancient Greek (古希腊的) physics．

    The scientist sometimes stops to look at very simple things and to think very hard about them．Even the simplest idea, which we might think is foolish, can shake the foundations (基础) of science．

    Riley read so many stories about pirates (海盗) and treasure chests that he wanted to find a treasure chest of his own. One day, Riley went to the library and read a story about a man that buried expensive gold coins in his backyard in a chest. Riley was so interested in the story. "Mom, tell him that treasure chests are only in books and movies," said his old brother Ted. "It could really happen," said Riley. "Riley's right," said mom. "If you believe in something strong enough, it could happen."

    That night Riley's mom told Riley's dad how much Riley wanted to find a treasure chest. "I have an idea," said Riley's mom. "Saturday is Riley's birthday. Let's put his gift in a treasure chest and bury it in the yard for him to find." "That's a great idea!" said Riley's dad. They decided to put his new watch in the treasure chest. They would give him a map with clues (线索 ) to look for the treasure chest outside.

    After Riley left for school the next day, his mom wrapped the watch and went to the party store to buy a treasure chest. She came home and buried the treasure chest underneath the oak tree. She then drew a map with clues to where the treasure chest was buried. When Saturday came, mom and dad gave Riley his map, and told him that he would have to find his gift in the treasure chest using the clues on the map. Riley was so excited! He anxiously followed all the clues and found the treasure chest with his new watch. "Wow!" said Riley. "This is fantastic! I knew I would find a treasure chest someday!"

    "Happy Birthday!" they all shouted.

    Today is the fifth day of July. It is Judy's birthday. When she comes back home from school, she sees a card on the table. It says, "There's a present(礼物)for you, Judy. Look for(寻找)it in your bedroom. "Judy runs in—to her bedroom. Her parents are looking at her and smiling. On the chair she sees a red box. She thinks her present is in it。She opens it, and there is a piece of paper in it. She reads it, "Dear Judy, I'm your present. My first letter(字母)is in the word 'dear', but not in 'pear'. My second letter is in 'red', but not in 'bed'. My third letter is in 'bus', and in' four'. And you can find my last letter in both(两者) 'home' and 'music'. What am I? "Judy thinks for a while and says, "Aha, I know. But where is it?" Her father tells her it is in her drawer.

    What is it? Do you know?

     Pan Changjiang is short and a little heavy. He has short straight hair. He is an actor and he is really funny. He also sings well.

     Liu Qian is a little thin and he is of medium height. He is good at magic. Many young people like him. He is very popular.

     Fei Xiang is tall and of medium build. He has long black hair. He is a famous singer and maybe our parents like his songs. He is handsome.

     Jackie Chan is a little heavy. He has a big nose. He is an actor and he is often in kung fu movies. He can sing well too.