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普特聽力短文：切洋蔥為什么會流淚
普特英語聽力是現在比較受學生歡迎的英語聽力材料之一，經常聽普特英語聽力確實對學生提高英語聽力有很好的好處。下面，小編就為大家送上一篇普特聽力短文，希望對大家有用。
普特聽力短文：
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.
參考譯文：
你考慮過為什么當你切洋蔥時，眼睛會留下淚水嗎?
如同催淚瓦斯
不管你怎么想，洋蔥的氣味并不會導致多數人流淚，你瞧，洋蔥的特殊味道來源于含有硫離子的復合物，當你切洋蔥時，你破壞了它的細胞，以至于激發化學反應，這種反應會使本身的化合物轉化成某種像催淚瓦斯一樣的酸。
與此同時，這種反應的副產品澤濃縮成為洋蔥刺激氣味的某種份子，換句話說，讓你淚眼汪汪以及釋放洋蔥味道的正是這種化學反應。
大蒜與健康
當你切蒜的時候也會發生類似的事情。當大蒜呈鱗球莖狀態時，氣味并不濃郁。只有當你切碎或者是破壞大蒜細胞時，化學反應釋才會放出大蒜的氣味。
但是，切片大蒜不會讓人流淚，這是因為在大蒜中發生化學反應的副產品同你切洋蔥時的得到的副產品不同。
科學家認為相同的化學反應賦予大蒜洋蔥獨特的氣味，這種氣味幫主它們擊退細菌，真菌以及寄生蟲。在關于大蒜洋蔥對你有好處報道的背后，或許有更多科學有待我們探究。
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