Gray hair is simply a part of the normal aging process, and the rate you go silver is genetically predetermined. Going gray is not associated with earlier death, and premature graying is not, generally speaking, a sign of an illness or ill health in younger adults. There are, however, some specific health conditions associated with gray or white hair, but for most of us, going gray is just a fact of life.
Hair color es from the pigment melanin(黑色素), which determines your individual shade. Hair without any melanin is pure white. The pigment is produced in cells called melanocytes, which inject pigment into the hair. At some point in everyone's lifetime, these cells slow down and eventually stop producing color. Scientists have yet to identify the exact mechanism by which melanocyte cell death occurs.
A study of more than 4,000 women and men from 20 countries determined that about 75% of people between the ages of 45 and 65 have some gray hair. In general, people of European descent gray earliest followed by Asians and Africans. It's interesting to note that a lucky 1 in 10 has no gray hair by retirement age. Beginning at age 30, your chances of having gray hair go up 10-20% per decade.
It may feel like you have more grays after a stressful event, but that's probably because middle age is basically a series of anxiety-ridden events. Between working, raising kids, and caring for older parents, the sandwich years of 45-65 can be stressful, especially for women. They are also when we naturally start to look older.
At this point, there is still no silver bullet to keep away the grays.
【小题1】What would be the best title for this passage? A．Going gray.B．Tips to make hair color lastC．Why does hair turn gray?D．Gray hair is in fashion.【小题2】Which of the following is a true statement according to the passage?A．Scientists have found out how to prevent hair from turning gray.B．Europeans are more likely to gray than Asians and Africans.C．Gray hair means poor health or a sign of illness.D．Everyone will inevitably get gray hair by retirement age.【小题3】Which is not among the reasons for hair turning gray according to the passage? A．Being physically weak.B．Stress from different sides.C．Death of melanocyte cell.D．Genetic factors.【小题4】What does “silver bullet” in the last paragraph probably mean?A．Make-upB．Scientific research.C．Chemical weapon.D．Cure.C
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(答案→)C
解析：本文介绍了为什么人的头发会变白。这是自然老化的过程、与基因有关，还和黑色素的分泌的多少有关，黑色素越少，头发越白。通过研究20多个国家的4000多男性和女性可知，有年龄原因也有地域原因。生活压力大也是原因之一。
【小题1】主题归纳题。根据全文尤其是文章的第一句话判断，文章是在讲头发变白的应用。所以选C。
【小题2】推理判断题。根据第三段的In general, people of European descent gray earliest followed by Asians and Africans.可知：欧洲人早于亚洲人和非洲人头发变花白。B
【小题3】细节理解题。根据第一段的内容可知，银发是一个正常老化的过程，头发变白由基因已经决定了的。与早亡无关，少白头也不是生病或者身体不舒服的标志。所以选A（身体虚弱）。
【小题4】词义推测题。根据最后一段的意思可知：人在45-65之间压力很大，尤其是妇女，还有自然的老化问题。所以选D（治愈）。其他选项的意思是：Make-up化妆；Scientific research.科学研究；Chemical weapon.化学武器。