What was discovered by accident? The answer is penicillin (青霉素). It kills germs. By killing germs, it saves lives. Suppose you are sick. You go to a doctor. She examines you. She says you have a “staph” infection (葡萄球菌感染). She gives you some medicine. You take it. The medicine knocks out the staph. Soon you are well. Before penicillin, this would not happen. Staph was almost sure death.

    Everyone wanted a medicine. Laboratories worked day and night. They grew the staph in small dishes. Then they tried to kill it. Nothing worked.

    The laboratory dishes had covers on them. They kept things from falling into dishes. Molds (霉菌) were a big worry. They are always in the air. You can't see them. They're too small. There are thousands of different molds. Molds can make an experiment (实验) fail. That's why dishes are covered.

    Dr. Alexander Fleming was working to kill the staph germ. He worked for years. One day he took a cover off a dish. He looked inside. There was a thick growth of staph germ. There was also some mold. Then he saw something strange. Where the mold was, there was no growth of staph. This is what Fleming probably thought. “By accident, I found a mold to kill the dreaded staph.”

    This is how penicillin was found. But here's the real miracle (奇迹). There are thousands of kinds of molds. But only one kind can kill staph. The mold must have fallen into the dish a few days before. The cover was probably off only a few seconds (秒). In those few seconds the right mold fell into the right dish. Another man might have thrown the dish away. But Fleming was very careful and smart. He understood what the mold did. How lucky the humans were!

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    By the time Rihanna was seventeen, she had released(发行)her first album and had an international hit with her first single(单曲)Pon de Replay.

    Rihanna was born in Saint Michael, Barbados in 1988.She grew up there with her two younger brothers. As a child, she loved singing. She formed her first group with two friends from secondary school when she was just fifteen. In 2004 her friends introduced the group to American record producer Evan Rogers, who was on holiday in Barbados. Rogers thought Rihanna could be a big star in America, so she moved there aged sixteen to take up music after she finished school. Rihanna lived with Rogers and his wife. Then she worked for Def Jam Recordings and started working on her first album, Music of the Sun. It came out in 2005 and got into the top ten. Over 69,000 copies of the album were sold in the first week alone. It went on to sell over two million copies worldwide and Rihanna quickly became a big star. Her second album, A Girl Like Me, came out a year later and included the song SOS, which was her first number one hit in America. In 2007 Rihanna brought out her third album, Good Girl Gone Bad, which had more dance music than the first two albums.

    Rihanna sold more than fifteen million albums and forty-five million singles worldwide between 2005 and 2010, the most of any artist at the same time. However, she manages to find time for her charity work, too. She has performed in several concerts to raise money for charity and in 2006 she created her Believe Foundation to help sick children. She also took part in Gucci's activities to raise money for children in Africa.

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