1. 
The two friends sat in a corner and _____ away to each other about the weather． 

2. 
He is going to _____ the meeting on the subject of war and peace in a minute． 

3. 
Although not an economist himself, Dr. Smith has long been a severe critic of the government's  _____ policies. 

4. 
There are not many teachers who are strong _____ of traditional methods in English teaching. 

5. 
A friendship may be  _____ , casual, situational or deep and lasting. 

6. 
Nobody yet knows how long and how seriously the shakiness in the financial system will  _____ down the economy. 

7. 
We are _____ to the idea, but we doubt whether the time is ripe to put it into force. 

8. 
People were surprised to find that Mr. Johnson had the ability to  _____  everything he was involved in. 

9. 
You can do it if you want to, but in my opinion it’s not worth the  _____ it involves. 

10. 
The manager gave one of the salesgirls an accusing look for  _____ her attitude toward customers. 

    Throughout history man has had to accept the fact that all living things must die. But people now live longer than they(1). Yet, all living things still show the(2)of aging, which will eventually(3)death. Aging is not a disease, （but）as a person passes maturity, the cells of the body and the(4) they form do not function as well as they(5) in childhood and teenage years. The body provides less(6)against disease and is more(7)to have accident. A number of related causes may(8)aging. Some cells of the body have a （fairly） long life, but they are not(9)when they die. As a person ages,(10)of brain cells and muscle cells decreases.(11)body cells die and are （replaced） by new cells. In an aging person the(12)cells may not be as workable or as capable(13)growth as those of a young person. Another(14)in aging may be changes within the cells(15). Some of the protein chemicals in cells are known(16)with age and become less elastic. This is why the skin of old people wrinkles and(17). This is also the reason why old people(18)in height. There may be other more important chemical changes in the cells. Some complex cell chemicals, such as DNA and RNA, store and(19)information that the cells need.Aging may affect this(20)and change the information carrying molecules so that they do not transmit the information as well.

    In the same way that a child must be able to move his arms and legs before he can learn to walk, the child must physiologically be capable of producing and experiencing particular emotions before these emotions can be modified through learning. psychologists have found that there are two basic processes by which learning takes place. one kind of learning is called "classical conditioning". this occurs when one event or stimulus is consistently paired with, or followed by, a reward or punishment, it is through classical conditioning that a child learns to associate his mother's face and voice with happiness and love, for he learns that this person provides food and comfort. negative emotions are learned in a similar fashion.

    The second kind of learning is called "operant conditioning." this occurs when an individual learns to do things that produce rewards in his environment and learns not to do things that produce punishments. for example, if a mother always attends to her baby when he cries and cuddles him until he is quiet, she may teach him that if he cries he will get attention from mother. thus, the baby will learn to increase his crying in order to have his mother more.

    Every day, we grow and have new experiences. we constantly learn by reading, watching television, interacting with some people, and so forth. this learning affects our emotions. why is it that we learn to like some people and dislike others? if a person is nice to us, cares about us, we learn to associate this person with positive feelings, such as joy, happiness, and friendliness. on the other hand, if a person is mean to us, does not care about us, and even deliberately does things to harm us, we learn to associate this person with negative feelings, such as unhappiness, discomfort, and anger.

    Any country has good reason to want its citizens to be as healthy as possible, since one of its greatest resources is an active population. No country wants its people to suffer unnecessarily from ill health. 

    This was the kind of thinking which led to the introduction of a health service in many countries. In Britain this has developed into a “Welfare State” in which all citizens, rich and poor alike, can get most health treatment free. The money for this is partially raised by contributions from employers and employees.

    As three decades have shown, such automatic arrangements are not always ideal and there are arguments for and against the Health Service. The number of patients treated every year and the cost of treatment are much greater than was estimated. This means that the people who work for the Health Service—doctors, nurses and other hospital staff—have much more routine work to do and as a result they have little time for preventive medicine. The Health Service does need more staff—a need that can only be met if more money is made available to it. 

    However, a powerful argument for the Health Service is that many people are able to receive expensive treatment which they could never afford themselves. Sometimes this free treatment is abused and people visit their doctors when they don’t really need to. Because they have so many patients, doctors cannot spend as long with each one as they would like, and some people prefer to pay for private treatment so that their doctors can give them more time. In fact, some wealthy people feel that they should pay, and so free more money for treatment to others. 

    Do we need laws that prevent us from running risks with our lives? If so, then perhaps laws are needed prohibiting the sale of cigarettes and alcoholic drinks. Both products have been known to kill people. The hazards of drinking too much alcohol are as bad or worse than the hazards of smiking too many cigarettes. All right then, let's pass a law closing the liquor stores and the bars in this country. Let's put an end once and for all to the ruinous disease from which as many as 10 million Americans currently suffer--alcoholism.
    
    But wait. We've already tried that. For 13 years, between 1920 and 1933, there were no liquor stores anywhere in the United States. They were shut down abilished by an amendment to the Constitution and by a law of Congress. After January 20, 1920, there was supposed to be no more manyfacturing, selling, or transporting of "intoxicating liquors". Without any more liquor, people could not drink it. And if they did not drink it, how could they get drunk? There would be no more dangers to the public welfare from drunkenness and alcoholism. It was all bery logical. And yet prohibition of liquor, beer, and wine did not work. Why?
       
    Because, law or no law, millions of people still liked to drink alcohol. And they were willing to take risks to get it. They were not about to change their tastes and habits just because of a change in the law. And gans of liquor smugglers millions of gallons of the outlawed beverages across the Canadian and Mexican borders. Drinkers were licky to know of an illegal bar that served Mexican or Canadian liquor. Crime and drunkenness were both supposed to decline as a rusult of prohibition. Instead, people drank nore alcohol than ever-often poisoned alcohol.

    As people continue to grow and age, our body systems continue to change. At a certain point in your life, your body system began to weaken. Your joint may become stiff. It may become more difficult for you to see and hear. The slow change of aging causes our bodies to lose some of their ability to bounce back from disease and injury. In order to live longer, we have always tried to slow or stop this process that leads us toward the end of our lives.

    Many factors contribute to your health. A well-balanced diet plays an important role. The amount and type of exercises you get is another factor. Your living environment and the amount of stress you are under is yet another. But scientists studying senescence want to know: Why do people grow old? They hope that by examining the aging process on a cellular level medical science may be able to extend the length of life.

    There is nothing to be afraid of as old age approaches. Many consider the later portions of life to be the best time for living. Physical activity may lessen, but often you gain a broader understanding of yourself and the world.
What we consider old age now may only be middle-aged someday soon. Who knows with so many advances in medical science happening so quickly, life spans may one day be measured in centuries, rather than in years!

51. 
    2013年12月份以来，中国25个省份、100多座大中城市再次遭遇雾霾侵袭。北京、上海、南京等相继沦陷为雾霾重灾区，湖北、浙江、湖南、江苏、安徽等地雾霾天创下历史纪录。国家气象局数据显示，今年以来中国平均雾霾天数已经创出52年来之最。

    虽然政府部门采取了工业企业关停减产的措施应对雾霾肆虐，但收效甚微，雾霾正在对人们的生活产生越来越多的负面效应：学校停课、汽车限行、高速封闭。而更让有关部门尴尬的是，制造出雾霾的空气污染物来源，目前仍然是一个迷。

    自京津冀频繁发生雾霾起，几年过去了，对于其形成的具体原因暂无定论。大多数的专家给出答案，重污染天气形成的主要原因有二：污染物排放总量过大和不利气象条件。具体看来，长三角周边更多为化工、水泥等企业，其工业废气组成更为复杂。

    当然，问题的复杂性从来不是延缓解决方案的借口。在历经了京津冀地区的雾霾恐慌后，今年9月国务院出台了《大气污染防止行动计划》，涉及包括京津冀、长三角和珠三角在内的重点控制区的水泥、化工等六大重污染行业以及燃煤工业锅炉的新建项目。

    从目前学界的研究来看，PM2.5的治理绝非易事。这样的长期计划要先布局，再行动，最后是对企业发力。

    类比国外相关案例，上个世纪四五十年，无论是代洛杉矶雾霾爆还是伦敦雾霾事件，最后都是在政府和企业合力后，达成协议，最后以《清洁空气法》等法案的形式完成监督。