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为什么切洋葱会流泪[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ #Ltj2r! P.$ y*az*FroG]
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洋葱营养价值高，是高血压、高血脂病人的绝佳保健食品。可是切洋葱的时候，总是会被洋葱的味道辣得流泪。想知道这是为什么吗？请看下面的文章。[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ :{ Zj 4k1[bWR"GQFroG]
It is not the strong odor of the onion that makes us cry, but the gas that the onion releases when we cut this member of the lily family.[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ !d3ss4Imn{!aA(OFroG]
The onion itself contains oil, which contains sulfur, an irritant to both our noses and to our eyes. Cutting an onion arouses a gas contained within the onion, propanethiol S-oxide, which then couples with the enzymes in the onion to emit a passive sulfur compound. When this upwardly mobile gas encounters the water produced by the tear-ducts in our eyelids, it produces sulfuric acid.[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ pOh7X@;hbl~qw?tko}"FroG]
In response to the caustic acid, our eyes automatically blink, and produce tears which irrigate the eye, and which flush out the sulfuric acid.[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ u;V_#T5/2(FroG]
Another reflex to rid the eyes of a foreign substance, that of rubbing our eyes with our hands, often exacerbates the situation, because our hands are coated with the caustic, sulfuric acid producing oil from cutting the onion, which we then rub directly into our eyes.[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ FZidtY#5'ou fXn? XFroG]
Much to our chagrin, the only remedy for ridding the onion of its pungent, irritating oil is to boil it, not to slice it or dice it.[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ m$SiSM Zr ~ k ^FroG]
sulfur: 硫磺[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ m@`pN�{+ *?j3aieFroG]
irritant: 刺激[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ 8` Z1+tR!._aVX(QAFroG]
enzyme: 酶[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ R x}pKrO[ Sd&qc*8FroG]
tear-duct: 泪管[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ :*pl&mqBUCXyn qFroG]
exacerbate: 加剧，恶化[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ zH= :H-H. :jO:hyFroG]
dice: 切成丁[文章版权 禁止转载:考试与评价 http://www.trgroup.com.cn/te/ N0y& $v)m :;nmFroG]
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