When an ice cream sundae(圣代冰淇淋) cost much less, a boy entered a coffee shop and sat at a table. A waitress put a glass of water in front of him.

    "How much is an ice cream sundae?"

    "Fifty cents," said the waitress.

    The little boy pulled his hand out of his pocket and studied a number of coins in it. "How much is a dish of plain ice cream?" he asked.

    Some people were waiting for a table, and the waitress was not patient. "Thirty-five cents," she said angrily.

    The little boy again counted the coins. "I will have the plain ice cream," he said. The waitress brought the ice cream and walked away. The boy finished, paid the money, and left.

    When the waitress came back, she was surprised at what she saw. There were fifteen cents placed beside the empty dish. That was her tip.

    Every year hundreds of people try to climb the world's highest mountain or walk through rainforests(雨林). Let's take a look at two of the 21st century's(世纪的) greatest adventurers(冒险家).

    A mountain climber

    Do you know that more than 4，000 people have climbed Mount Everest? Gerlinde is one of them. She is one of the world's greatest climbers and has climbed all the mountains over 8，000 meters in the world. It's difficult to climb mountains in cold weather, but Gerlinde loves it. She started climbing the mountains near her home as a teenager. When she left school, she became a nurse but always went climbing in her free time.

    An Amazon adventurer

    Ed Stafford is the first person to walk along the Amazon River from the mountains of Peru to the mouth of the river in Brazil. His journey took two years and four months. There are many dangerous animals in the rainforest. But Ed was lucky and he was only bitten(咬) by small insects(昆虫). On his trip, Ed had to look for fruit or catch fish each morning. Sometimes food was hard to find and Ed was often tired and hungry. So he used a radio to ask the people of the rainforest for food and help.

    On October5, Tu Youyou, 84, became the first Chinese to win a Nobel Prize in natural science. She is only the12th woman in history to be awarded the honor.

    Tu was born in Ningbo, Zhejiang, China on 30 December 1930. She once studied at Xiaoshi Middle School and Ningbo Middle School. Her teacher said that Tu liked reading books and she was very hard-working. From 1951 to 1955, she attended Beijing Medical College. Later Tu was trained for two and a half years in traditional Chinese medicine.

    Tu was given the award for her discovery of artemisinin(青蒿素), which has been developed to fight against malaria(疟疾). When Tu started her search in the late 1960s, over 240,000 compounds(化合物) around the world had already been tested, without any success. Her interest in traditional Chinese medicine drew her to ancient texts and finally found the sweet wormwood(青蒿),which had been used to treat malaria in China around 400 A.D. After more than190 failures, she invented the right drug in 1971.

    Tu Youyou doesn't have a Ph.D., neither has she ever studied or worked overseas. One former colleague, Liao Fuming, who has worked with Tu for more than 40 years, describes her as a "tough and stubborn(固执) woman."

    Tu is stubborn enough to spend many years putting ancient texts together and use them in modern scientific practices. The result is millions of lives saved.

    "She has done wonderful contribution to the world with her work, she really deserves it! It's a blessing for the Chinese people, as it is for the world!" Mats Wahlgren, member of the Nobel Assembly said.

    Jerry has a happy family — his parents, his sister and he. They live in a small town, and it is not far from the city.

    One day, Jerry goes to a shopping centre in the city to buy a new pair of trousers. There are too many people in the shop, so he doesn't want to try them on there.

    He goes back home and tries on the trousers in his bedroom. They are too long for him and he wants to ask his mother or sister to shorten (剪短) them for him. When he goes to his mother, she is cooking lunch and doesn't have any time to help him. He goes to his sister, but she is washing clothes and shoes. "The new trousers are too long. Can you help me to shorten them five centimetres?" His mother and sister are busy, and they don't say anything. Jerry goes out to fly kites with his classmates.

    Jerry's father is not busy, so he helps his son to shorten the trousers and plays computer games again in the study. When his mother finishes cooking, she goes to Jerry's bedroom and helps him to shorten the trousers five centimetres, too. But she doesn't tell her daughter about it and goes out.

    After an hour, Jerry's sister remembers her brother's trousers. So she goes quietly into the room and also helps her brother to shorten the trousers five centimetres.

    Can you guess the look on Jerry's face when he wears the trousers next time?