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洪恩朗文3L看听学英语第四册 Lesson 53
Lesson 53 Television Day: Penicillin
TV Commentary:
If you leave a piece of bread in a warm damp place, mould will soon grow in it. When this happens, we say that bread "has gone mouldy". Mould can grow on all kinds of things besides food-on leather, clothing, even on wood. It grows from tiny spores which are in the air. Each spore is like a little mushroom. If the conditions are right, a single spore can quickly spread and form a mould. It is extremely common and we have all noticed it.
In 1928, Sir Alexander Fleming found that mould and killed some germs he was trying to grow in his laboratory. If he had not noticed this, the world would have lost one of the greatest discoveries of the century. Fleming called the substance "penicillin". Because penicillin can kill germs, doctors use it to treat diseases. It has saved millions of lives. Scientists grow enormous quantities of common mould so that they can get penicillin from it in order to make antibiotics, that is, substances that kill germs. Next time you see some mould on a piece of bread, remember that it is one of man's greatest friends!
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