普特听力短文：切洋葱为什么会流泪

　　普特英语听力是现在比较受学生欢迎的英语听力材料之一，经常听普特英语听力确实对学生提高英语听力有很好的好处。下面，小编就为大家送上一篇普特听力短文，希望对大家有用。

普特听力短文：切洋葱为什么会流泪

　　普特听力短文：

　　Have you ever wondered why your eyes water when you chop onions?

　　Like Tear Gas

　　Despite what you might think, the smell of onions is not what makes most people cry. You see, an onion gets it distinctive taste from compounds that contain sulfur atoms. When you slice an onion, you damage its cells, triggering a chemical reaction that converts these compounds into an acid that acts like tear gas.

　　At the same time, the byproducts of this reaction condense to form the molecules responsible for the onion’s pungent odor. In other words, the same chemical reaction that makes you weepy also releases the onion’s smell.

　　Garlic And Health Benefits

　　A similar thing happens when you chop garlic. When it’s still in bulb form, garlic doesn’t smell like much. It’s only when you mince or dice the garlic’s cells that a chemical reaction releases the smell we associate with garlic.

　　However, no one cries from slicing garlic. This is because the byproducts of the chemical reaction that takes place in garlic are different from the byproducts you get when you chop an onion.

　　Scientists suggest that the same chemical that gives garlic and onions their distinctive smell helps them fight off bacteria and fungus and parasites. There might be something after all behind all those reports that garlic and onions are good for you.

　　参考译文：

　　你考虑过为什么当你切洋葱时，眼睛会留下泪水吗?

　　如同催泪瓦斯

　　不管你怎么想，洋葱的气味并不会导致多数人流泪，你瞧，洋葱的特殊味道来源于含有硫离子的复合物，当你切洋葱时，你破坏了它的`细胞，以至于激发化学反应，这种反应会使本身的化合物转化成某种像催泪瓦斯一样的酸。

　　与此同时，这种反应的副产品泽浓缩成为洋葱刺激气味的某种份子，换句话说，让你泪眼汪汪以及释放洋葱味道的正是这种化学反应。

　　大蒜与健康

　　当你切蒜的时候也会发生类似的事情。当大蒜呈鳞球茎状态时，气味并不浓郁。只有当你切碎或者是破坏大蒜细胞时，化学反应释才会放出大蒜的气味。

　　但是，切片大蒜不会让人流泪，这是因为在大蒜中发生化学反应的副产品同你切洋葱时的得到的副产品不同。

　　科学家认为相同的化学反应赋予大蒜洋葱独特的气味，这种气味帮主它们击退细菌，真菌以及寄生虫。在关于大蒜洋葱对你有好处报道的背后，或许有更多科学有待我们探究。

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