作者：圣才电子书
出版社：圣才电子书
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2017年全国职称英语等级考试（卫生类A级）历年真题及模拟试题详解试读：
视频讲解教师简介
沈冰洁，大学讲师，北京第二外国语学院应用英语学院外国语言学及应用语言学专业文学硕士。教学经验丰富，在校内主要教授本科生、专科生商务英语、基础英语以及四六级课程。学习成绩优异，高分通过英语专业八级、剑桥商务英语高级等考试。
授课特点：讲解细致，课堂节奏流畅，对知识点、考点把握精准，注重课堂学习效率。
第一部分 历年真题及详解[视频讲解]
2016年全国职称英语等级考试（卫生类A级）真题及详解
第1部分：词汇选项（第1—15题，每题1分，共15分）
下面每个句子中均有1个词或短语画有底横线，请为每处画线部分确定1个意义最为接近的选项。
1. She is an artist whose work will undoubtedly withstand the test of time.
A. grade
B. attract
C. bear
D. suffer【答案】C【解析】句意：她是位艺术家，毫无疑问，她的作品将经受得住时间的考验。withstand抵挡，禁得起。bear忍受。两者意思相近，可相互替换。grade评分；分等级。attract吸引。suffer遭罪，受苦。因此，本题正确答案为C。
2. He wore a shabby thin overcoat in the cold winter so that he fell ill.
A. big
B. new
C. small
D. old【答案】D【解析】句意：寒冷的冬天里他穿着一件又旧又破的外套，导致他生病了。shabby破旧的，故老的。old老的，旧的。两者意思相近，可相互替换。big巨大的。new新的。small小的。因此，本题正确答案为D。
3. They have built canals to irrigate the desert.
A. water
B. decorate
C. change
D. visit【答案】A【解析】句意：他们已经修建了可以灌溉荒漠的运河。irrigate灌溉，与water灌溉，浇水。两者意思相近，可相互替换。decorate装饰。change改变，变化。visit参观，访问。因此，本题正确答案为A。
4. We are worried about this fluid situation full with uncertainty.
A. changeable
B. stable
C. suitable
D. adaptable【答案】A【解析】句意：我们很担心这个充满未知的动荡局势。fluid易变的，不固定的。changeable可变的，易变的。两者意思相近，可相互替换。stable稳定的,牢固的。suitable合适的。adaptable可适应的,适应性强的。因此，本题正确答案为A。
5. The way she looked after her young sister was really touching.
A. disturbing
B. connecting
C. waving
D. moving【答案】D【解析】句意：她照顾她妹妹的方式令人感动。touching令人同情的；感人的。moving令人感动。两者意思相近，可相互替换。disturbing令人烦扰的。connect连接。waving摇动的，波浪状的。因此，本题正确答案为D。
6. His answers were obscure and confusing.
A. obvious
B. unclear
C. clear
D. direct【答案】B【解析】句意：他的回答晦涩难懂，令人难以理解。obscure晦涩的，不清楚的。unclear不清楚的。两者意思相近，可相互替换。obvious明显的。clear清晰的。direct直接的。因此，本题正确答案为B。
7. Some newspapers in the west are notably biased.
A. wholly
B. totally
C. especially
D. fairly【答案】C【解析】句意：西部的一些报刊显著带有偏见。notably显著地；尤其。especially特别，尤其。两者意思相近，可相互替换。wholly完全地，全部。totally完全地，总共。fairly相当，公平地。因此，本题正确答案为C。
8. Only people over 18 are eligible to vote.
A. honest
B. enabled
C. clever
D. qualified【答案】D【解析】句意：只有年满18岁的人才有选举的资格。eligible符合条件的；有资格当选的。qualified有资格的。两者意思相近，可相互替换。honest诚实的，坦率的。enabled可行的。clever聪明的，机智的。因此，本题正确答案为D。
9. Competitors must abide by the judge’s decision.
A. keep
B. read
C. understand
D. obey【答案】D【解析】句意：参赛者必须遵守裁判的决定。abide by遵守，服从。obey遵守，遵循。两者意思相近，可相互替换。keep保持；留下。read阅读。understand理解，知道。因此，本题正确答案为D。
10. The coastal area has very mild winter, but the central plains remain extremely cold.
A. severe
B. hard
C. warm
D. dry【答案】C【解析】句意：沿海地区冬季温和,但中部平原地区冬季却十分寒冷。mild温和的。warn温暖的。两者意思相近，可相互替换。severe严峻的，严重的。hard困难的；坚硬的。dry干燥的。因此，本题正确答案为C。
11. The weather was so gorgeous that many people went outing.
A. pleasant
B. uncontrollable
C. cloudy
D. unbearable【答案】A【解析】句意：天气很好，所以很多人都外出郊游。gorgeous华丽的，灿烂的；极好的。pleasant令人愉快的，舒适的。两者意思相近，可相互替换。uncontrollable难以控制的。cloudy多云的。unbearable难以忍受的。因此，本题正确答案为A。
12. The umbrella was ingeniously devised to fold up into the pocket.
A. seriously
B. cleverly
C. attentively
D. carefully【答案】B【解析】句意：雨伞设计巧妙，可以折叠后放人口袋里。ingeniously巧妙的，机灵的。cleverly巧妙的，聪明的。两者意思相近，可相互替换。seriously严重地，严肃地。attentively聚精会神地。 carefully认真地，小心翼翼地。因此，本题正确答案为B。
13. The latest car model embodies the new research development.
A. includes
B. lists
C. borrows
D. broadens【答案】A【解析】句意：最新的车型体现了新研究的发展。embody体现，使具体化，包含。include包含，包括。两者意思相近，可相互替换。list把……列入名单。borrow借。broaden扩宽,开阔。因此，本题正确答案为A。
14. The new garment fits her perfectly.
A. haircut
B. clothes
C. purse
D. necklace【答案】B【解析】句意：这身新衣服很适合她。garment衣服，服装。clothe衣服。两者意思相近，可相互替换。haircut理发，发型。purse女式钱包。necklace项链。因此，本题正确答案为B。
15. The details of the costume were totally authentic.
A. real
B. outstanding
C. creative
D. false【答案】A【解析】句意：道具服装的细节十分逼真。authentic真正的，真实的。与real真实的。意思相近，可相互替换。outstanding杰出的，突出的。creative富有创造力的。false错误的，假的。因此，本题正确答案为A。
第2部分：阅读判断（第16—22题。每题1分，共7分）
下面的短文后列出了7个句子，请根据短文的内容对每个句子做出判断：如果该句提供的是正确信息，请选择A；如果该句提供的是错误信息，请选择B；如果该句的信息文中没有提及，请选择C。Scientists Develop Ways of Detecting Heart Attack
German researchers have come up with a new generation of defibrillators（除颤器）and early-warning software aimed at offering heart patients greater protection from sudden death from cardiac arrest (心脏骤停).
In Germany alone around 100,000 people die annually as a result of cardiac arrest and many of these cases are caused by disruption to the heart’s rhythm. Those most at risk are patients who have already suffered a heart attack, and for years the use of defibrillators has proved useful in diagnosing life-threatening disruptions to heart rhythms and correcting them automatically by intervening within seconds. These devices take on a range of functions, such as that of pacemaker.
Heart specialists at Freiburg’s University Clinic have now achieved a breakthrough with an implanted defibrillator capable of generating a six-channel electrocardiogram （ECG） within the body. This integrated system allows early diagnosis of acute blood-flow problems and a pending （潜在的）heart attack. It will be implanted in patients for the first time this year. Meanwhile, researchers at the Fraunhofer Institute for Applied Mathematics in Kaiserslautem have developed a new computer software that renders the evaluation of ECG data more precise.
The overwhelming majority of patients at risk will not have an implanted defibrillator and must for this reason undergo regular ECGs. “Many of the current programs only take into account a linear correlation of the data. We are, however, making use of a non-linear process that reveals the chaotic patterns of heart beats as an open and complex system,” Hagen Knaf says. “In this way changes in the heart beats over time can be monitored and individual variations in patients taken into account.” An old study of ECG data, based upon600 patients who had suffered a subsequent heart attack, enabled the researchers to compare risks and to show that the new software evaluates the data considerably better.
16. A new type of defibrillators can be used to prevent cardiovascular diseases.
A. Right
B. Wrong
C. Not mentioned
17. Cardiac arrest is caused mostly by disruption to the heart’s rhythm.
A. Right
B. Wrong
C. Not mentioned
18. Defibrillators are useful in curing patients constantly under the threat of heart attack.
A. Right
B. Wrong
C. Not mentioned
19. The new computer software is designed by a German Company.
A. Right
B. Wrong
C. Not mentioned
20. The non-linear process has taken into account the individual variations in patients.
A. Right
B. Wrong
C. Not mentioned
21. The early-warning software is unique in its data collection.
A. Right
B. Wrong
C. Not mentioned
22. The researchers proved the validity of the new software via ECG data of an old study.
A. Right
B. Wrong
C. Not mentioned【答案与解析】
16. A 定位根据关键词a new type of defibrillators和prevent cardiovascular diseases可定位至第一段。
点睛根据文章第一段，德国研究者们发明了新一代的除颤器和早期预警软件，旨在为心脏病帮人提供更多的保护，使他们免遭心脏骤停导致的突然死亡。由此可知，本题说法是正确的。因此，本题正确答案为A。
17. A 定位根据关键词由cardiac arrest和the heart's rhythm可定位至第二段第一句。
点睛该句提到“In Germany alone around 100,000 people die annually as a result of cardiac arrest and many of these cases are caused by disruption to the heart’s rhythm(仅在德国每年就有大约10万人死于心脏骤停，其中 大部分是由于心律中断导致的)”， 由此可知，本题说法是正确的。因此，本题正确答案为A。
18.В 定位根据关键词defibrillators are useful和the threat of heart attack可定位至第二段第二句。
点睛该句提到“Those most at risk are patients who have already suffered a heart attack, and for years the use of defibrillators has proved useful in diagnosing life（几年来除颤器被证实在诊断心律中断方面是有用的）”，文中说的是诊断和调整心率而非治疗，由此可知，本题说法是错误的。因此，本题正确答案为B。
19. В 定位根据关键词new computer software可定位至第三段第四句。
点睛该句提到“Meanwhile，researchers at the Fraunhofer Institute for Applied Mathematics in Kaiserslautern have developed в new computer software（同时，凯瑟劳特的弗劳胡佛实用数学学院的研究者开发了一种新计算机软件）”，研究者开发了一种新计算机软件而非公司。由此可知，本题说法是错误的。因此，本题正确答案为B。
20.А 定位根据关键词a non - linear process和individual variations in patients可定位至第四段第三句。
点睛该句提到“We are，however，making use of a non-linear process Hagen Knaf says. u In this way changes in the heart beats over time can be monitored and individual variations in patients take into account（现在使用的是非线性处理方法，这样心脏跳动 频率的变化就会受到监控，而病人个人的特征也会得到考虑）”，由此可知，本题说法是正确的。因此，本题正确答案为A。
21.C 点睛本文并未提及“早期预警软件有着独特的数据收集方法”，因此，本题正确答案为C。
22.A 定位根据关键词ECG data of an old study可定位至第四段最后一句。
点睛该句提到“An old study of ECG data, based upon 600 patients who had suffered a subsequent heart attack, enabled the researchers to compare risks and to show that the new software evaluates the data considerably better（过去一项基于600位连续犯心脏病的患者的研究让研究人员们可以对风险进行比较，结果显示新软件明显能更好地处理心电图数据。）”，由此可知，本题说法是正确的。因此，本题正确答案为A。【全文翻译】科学家探索检测心脏病的方法
德国研究人员研发出了新一代除颤器和预警软件，旨在更好的保护心脏病患者，防止因心脏停搏而突然死亡。
仅仅在德国，每年就有约10万人死于心脏骤停，其中大部分是由于心率中止导致的。最危险的是那些已经犯过一次心脏病的人。多年来，除颤器的使用在诊断要命的心率中止以及在几秒钟之内自动干预并矫正心率方面是非常有用的。这些设备有一系列功能，比如相当于起搏器的功能。
弗莱堡大学诊所的心脏病专家已经在植入式心律除颤器方面取得了突破性的进展，这种心律除颤器可以在体内产生六通道型的心电图。这种集成系统能够提前诊断出严重的血液流通问题和即将发生的心脏病。这种仪器今年将首次植入病人体内。与此同时，凯泽斯劳滕的弗劳恩霍夫研究所应用数学部的研究人员已经开发出了一种新的计算机软件，此软件可以使心电图数据的评估更加精确。
大多数危险的患者都没有植入式除颤器，所以他们必须接受常规心电图检查。“现有的许多程序只考虑线性相关性数据，但是我们现在使用的是能够将心脏跳动的混乱模式作为一个直观而又复杂的系统解释出来的非线性处理方法，”Hagen Knaf说。通过这种方式可以随时监测心跳的变化，个体差异因素也会被考虑在内。过去一项基于600位连续犯心脏病的患者的研究让研究人员们可以对风险进行比较，结果显示新软件明显能更好地处理心电图数据。
第3部分：概括大意与完成句子（第23—30题，每题1分，共8分）
下面的短文后有2项测试任务：（1）第23～26题要求从所给的6个选项中为第2～5段每段选择1个最佳标题；（2）第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。Sleep Well to Be Well
1 Do you often feel tired in the morning even though you’ve been in bed for seven or eight hours the night before？ Like many people, you are not sleeping as much as you think you are. In other words, your sleep efficiency is not that good.
2 Sleep experts define “sleep efficiency” as the percentage of time lying down that you are actually sleeping. According to the Explanatory Journal, the science of sleep efficiency is still young. There is no specific number for efficiency that’s been proven as linked to poor health. However, according to a New York Times report about sleep quality, some experts estimate a rough ballpark（范围）of 85 percent or above as a decent place to be.
3 Short wavelength blue light, emitted（放出） by the sun and by the screens of computers, iPads and smartphones, stops production of the sleep-inducing hormone melatonin （褪黑素） and makes you feel more active. Blue light tells your brain it’s daytime. Experts suggest turning off your computers and smartphones one hour or at least 30 minutes before bed.
4 Go to bed and wake up at the same time, or relatively the same time, every day. Avoid binge sleeping（狂睡）on the weekend. Consistency is the key to a good night’s sleep, especially when it comes to waking up. When you have a consistent wake-up time, your brain accustoms to this and moves through the sleep cycle in preparation for you to feel rested and active at your wake-up time.
5 One of the biggest peaks in melatonin production happens during the 1 to 3 pm time frame, which explains why most people feel sleepy in the afternoon. If you aren’t getting enough sleep at night, you’re likely going to feel an overwhelming desire to sleep in the afternoon. When this happens, you’re better off taking a short nap than resorting to caffeine or strong tea to keep you awake. A short nap will give you the rest you need to get through the rest of the afternoon, and you’ll sleep much better in the evening than if you drink caffeine or take a long afternoon nap.
A. Define the sleep related terms
B. Take naps
C. Turn off the devices emitting blue light
D. Keep a consistent sleep schedule
E. Improve sleep quality
F. Avoid blue-light at night
23. Paragraph 2_________
24. Paragraph 3_________
25. Paragraph 4_________
26. Paragraph 5_________【答案与解析】
23.A 本段主要介绍了“睡眠效率”的定义，也就是与睡眠有关的术语，因此，正确答案为A。
24.C 本段主要介绍了“太阳和电子设备屏幕发出的短波长蓝光会影响睡眠，影响褪黑素的产生，让你感觉更清醒，所以专家建议睡前一小时或至少睡前30分钟关闭电脑和手机”。因此，正确答案为C。
25.D 本段主要提出建议，每天要规律睡眠,避免周末狂睡。坚持固定时间睡觉，这样大脑就会形成睡眠循环，到时间也会自然醒来。D项规律睡眠的重要性是对本段内容的概括，因此，正确答案为D。
26.B 本段主要介绍“下午1到3点是褪黑素的分泌高峰期，所以人容易犯困。如果晚上睡眠不够，这时候就可以小睡一下，这比喝咖啡或浓茶要好”。B项中午小睡是对本段内容的概括，因此，正确答案为В。
27. The tiredness in the morning even after many hours in bed is due to＿＿＿＿.
28. Sleeping less than 85% of the time spent lying in bed might cause＿＿＿＿.
29. A lower production of the hormone melatonin is due to＿＿＿＿.
30. A strong desire to sleep in the afternoon is the result of＿＿＿＿.
A. a long afternoon nap
B. the peak production of melatonin
C. poor health
D. low sleep efficiency
E. good sleep efficiency
F. exposure to blue light【答案与解析】
27. D 定位根据题干定位至第一段。
点睛该段第一句话提到睡得时间长还是会觉得疲倦'的原因是睡眠效率低，D项low sleep efficiency与原文说法一致。因此，正确答案为D。
28.C 定位根据题干定位至第二段。
点睛该段第二句话提到一些专家认为如果想要保持良好状态，这一比例约为85%或更高，C项poor health符合文意。因此，正确答案为C。
29. F 定位根据题干定位至第三段。
点睛该段第一句话提到来自太阳、电脑、平板电脑或手机屏幕的短波长蓝光会抑制促进睡眠的褪黑色素的产生,让你毫无睡意F项exposure to blue light符合文意。因此，正确答案为F.
30.В 定位根据题干定位至第五段。
点睛该段第一句话提到褪黑素产生的高峰是每天下午1点到3点。这也是大部分人会在下午感到困倦的原因，B项the peak production of melatonin与原文说法一致。因此，正确答案为B。【全文翻译】睡得多不如睡得好
1. 你是不是常常觉得即使晚上已经睡了七八个小时，白天依旧无精打采？你不是一个人，很多人都和你一样，因为你的（有效）睡眠时间并没有你想象的那么长。简言之，你的睡眠质量不够高。
2. 睡眠专家对“睡眠效率”的定义是真正睡眠时间占在你躺在床上时间的比例。据解释性新闻网站的报道，关于睡眠质量的研究起步较晚。目前尚无具体比例说明睡眠效率将会有害健康。但是，据《纽约时报》报道，一些专家认为如果想要保持良好状态，这一比例为85％或更高。
3. 来自太阳和电子设备屏幕发出的短波长蓝光会影响睡眠，影响褪黑素的产生，让你感觉更清醒，蓝光会让你的大脑误以为此时是白天。专家们的建议是：睡前一小时或至少睡前30分钟关闭电脑和手机。
4. 每天最好在同一时间入睡和起床，至少保持相对的一致性。不要在周末睡的太放纵，因为固定的睡眠时间，尤其是固定的清醒时间是睡眠的关键。当你拥有固定的睡眠时间时，你的大脑就会形成习惯，在入睡前为入睡状态做好准备，在醒来时恢复清醒。
5. 下午1到3点是褪黑素的分泌高峰期，所以人容易犯困。如果晚上睡眠不够，那么第二天下午你会困意十足，这时候就可以小睡一下，这比喝咖啡或浓茶要好。与喝咖啡或是在下午睡很久相比，小眯一会不仅让你得到充分的休息，还能保证你当天晚上的睡眠。
第4部分：阅读理解（第31~45题，每题3分，共45分）
下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
第一篇 Can Added Calcium Help Older Bones？
New Zealand researchers say guidelines advising seniors to consume at least 1,000 to 1,200 milligrams of calcium a day are misplaced.
No proof was found that boosting calcium intake beyond normal dietary levels strengthens older bones or prevents fractures, said researcher Dr Mark Bolland, a professor at the University of Auckland. “We’ve gathered all the clinical studies of calcium supplements and dietary calcium intake for both bone density and fractures,” said Bolland. “Taken together, we think this is the strongest possible evidence that taking calcium supplements will not be beneficial unless there are clear medical reasons that a calcium supplement is needed,” he said.
Moreover, excess calcium supplementation can be harmful, he and other experts said. “The findings probably will surprise clinicians and patients”, Bolland said, “because they have received very strong messages for many years about the importance of calcium for bone health in guidelines for osteoporosis（骨质疏松症）management and by osteoporosis advocacy groups.”“Clinical trials have shown that calcium supplements often cause minor gastrointestinal（胃肠的）side effects such as constipation（便秘）”, Bolland said. “They also cause a small increased risk of kidney stones, heart attacks, high calcium levels and hospitalization with acute gastrointestinal symptoms.” He also said. “The small risk of these important adverse effects, together with the moderate risk of minor side effects such as constipation, outweighs any benefits of calcium supplements on fracture.”
However, Dr Duffy MacKay, president for the Council for Responsible Nutrition, disagreed with Bolland’s conclusions, and countered that scientific evidence does show that calcium reduces fracture risk. “The degree of benefit varies from study to study,” he said. “However, the largest benefit is generally found in those who take their calcium supplements throughout the entirety of a study. Other important factors that influence the benefit of calcium supplementation include giving calcium supplements with other important bone nutrients including vitamin D and vitamin K.”
31. Dr Bolland says that calcium intake beyond normal dietary levels has _____.
A. a positive effect on older hones
B. an effective power on healing fractures
C. not been beneficial to the legs
D. not been proved effective
32. The clinical studies have been gathered to investigate _____.
A. both calcium supplements and calcium intake
B. either calcium supplements or calcium intake
C. either bone density or fractures
D. both bone density and fractures
33. The findings about the excess calcium intake are surprising because they are _____.
A. put forward by famous researchers
B. advocated in the guidelines for bone health
C. different from the long-standing concepts
D. only discussed within a few years
34. The adverse effects from the calcium supplements include the following EXCEPT _____.
A. constipation
B. forgetfulness
C. heart attacks
D. kidney stones
35. According to Dr MacKay, the most important factor affecting the result of the study is _____.
A. the continuous intake
B. the amount of intake
C. the age of patients
D. the gender of patients【答案与解析】
31.D 定位根据calcium intake beyond normal dietary levels定位到原文第二段。
点睛由第二段第一句博兰德博士的话“No proof was found that boosting calcium I intake beyond normal dietary levels strengthens older bones or prevents fractures, said researcher Dr Mark Bolland, a professor at the University of Auckland. ”可知，并没有证据表明超过每日所需摄人量的钙能够强健骨骼或是预防骨折。只有D符合题意，故选D。
避错A、B两项与原文意思相反，C项原文未提及。
32.D 定位根据clinical studies have been gathered定位到原文第二段。
点睛第二段第二句“We’ve gathered all the clinical studies of calcium supplements and dietary calcium intake for both bone density and fractures”可知，研究者针对转补剂和饮食钙摄入对骨密度与骨折的影响展开临床研究，就是为了调查钙摄入与骨密度、骨折的关系。故本题的答案是D。
避错A、B两项说的转补剂和饮食钙摄入是展开研究的主题，而非研究的对象。原文是针对钙摄入与骨密度、骨折的两者的关系，而非二者之一。故C项错误。
33.C 定位根据excess calcium intake are surprising定位到原文第三段。
点睛第三段提到“The findings probably will surprise clinicians and patients”，Bolland said，“because they have received very strong messages for many years about the importance of calcium for bone health in guidelines for osteoporosis management and by osteoporosis advocacy groups. ”可知，研究结果惊人之处就在于它颠覆了长期以来人 们强调补钙对于骨质疏松症有利的认识，这与之前的认知概念很不一样。故本题的答案是C。
避错A、B、D项未提及。
34.B 定位根据adverse effects定位到原文第四段。
点睛根据“They also cause as mall increased risk of kidney stones, heart, attacks, high calcium levels …The small risk of these important adverse effects, together with the moderate risk of minor side effects such as constipation, outweigh any benefits of calcium supplements fracture. ” 可知，钙补剂的副作用并没有健忘。故本题的答案是B。
避错A、C、D在原文都有提及，题干出现except故排除B。
35.A 定位根据according to Dr. MacKay定位到原文最后一段。
点睛根据麦凯博士的看法，由“The degree of benefit varies from study to study," he said. However, the latest benefit is generally found in those who take their calcium supplements throughout the entirety of a study. ” 可知，结果因研究而异，研究证据表明补钙确实能降低骨折风险，大多数受益者反倒是坚持补钙的人群，所以应该是持续性摄人对研究结果的影响最大，故本题的答案是A。
避错B、C、D项未提及。【全文翻译】多余钙的摄入有利于老年人的骨骼吗？
新西兰研究人员分析了以前的100多个调查，指出老年人每天至少消耗1000到1200毫克的钙，这种建议的参考性是错误的。
研究员马克博兰博士说到，没有证据表明，多余钙的摄入量超过正常饮食水平可以增健老年人的骨骼或防止骨折。“我们已经收集了所有的骨密度和骨折的膳食摄入钙和补充钙的临床研究，”奥克兰大学医学系副教授博兰说。总之，“我们认为这是最强有力的证据表明，服用钙补充剂将不会对身体是有益，除非有明确的补充钙必要的医疗原因”，他说。
此外，过量的补充钙可能是有害的，他和其他专家说到。“该发现可能会会使临床医生和患者感到惊讶”，兰德说，“因为他们已经掌握大量的信息，关于多年来补钙对于治疗骨质疏松的骨骼健康的重要性”，并已被骨质疏松的团体所认可。“临床试验表明，钙补充剂通常会引起轻微的胃肠道不适反应，如便秘”，兰德说。“他们也很有可能会诱发肾结石，心脏病、高钙水平与需要住院治疗的急性胃肠道症状。”他还说。“这些小风险重要的副作用，加上如便秘的中等风险轻微的副作用，超过钙补充剂对骨折本身的益处。”
然而，杜菲麦凯，负责营养的科学监管事务委员会主席，不同意博朗的结论，并反驳说，科学证据表明，钙可以降低骨折的风险。所做研究不同，显现出的利益的程度各不相同， “他说。”然而大多数受益者 反倒是坚持补钙的人群。影响补充钙吸收的其他重要因素包括补充维生素D和其他重要的骨骼营养素的摄取，包括维生素D和维生素K的摄入。
第二篇 Deforestation and Desertification（沙漠化）
The Sahel zone lies between the Sahara desert and the fertile savannahs（热带大草原）of northern Nigeria and South Sudan. The word sahel comes from Arabic and means marginal or transitional, and this is a good description of these semi-arid（半干旱） lands, which occupy much of the Western African countries of Mali, Mauritania, Niger, and Chad.
Unfortunately, over the last century the Sahara desert has steadily crept southwards eating into once productive Sahel lands. United Nations surveys show that over 70 percent of the dry land in agriculture use in Africa has deteriorated over the last 30 years. Droughts have become more severe, the most recent lasting over twenty years in parts of the Sahel region. The same process of desertification is taking place across southern Africa as the Kalahari desert advances into Botswana and parts of South Africa.
One of the major causes of this desert advance is poor agricultural land use, driven by the pressures of increasing population. Overgrazing-keeping too many farm animals on the land-means that grasses and other plants cannot recover, and scarce water supplies are exhausted. Overcultivation—trying to grow too many crops on poor land—results in the soil becoming even less fertile and drier, and beginning to break up. Soil erosion（侵蚀）follows; and the land turns into desert.
Another cause of desertification is loss of tree cover. Trees are cut down for use as fuel and to clear land for agricultural use. Tree roots help to bind the soil together, to conserve moisture, and to provide a habitat for other plants and animals. When trees are cut down, the soil begins to dry and loosen, wind and rain erosion increase, other plant species die, and eventually the fertile topsoil may be almost entirely lost, leaving only bare rock and dust.
The effects of loss of topsoil and increased drought are irreversible. They are, however, preventable. Careful conservation of tree cover and sustainable agricultural land use have been shown to halt deterioration of soils and lessen the effects of shortage of rainfall.
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