填空题That can be a good thing, with the Web serving as a kind of buffer zone (缓冲地带) for uncomfortable interaction. It's easier to face rejection, there aren't lulls in conversation or geographic boundaries - and social networking is like a window into the lives of potential mates. Say two people meet on Facebook, though a mutual friend. Immediately, they know whether the other person is single - without having to ask. ______ It's all the details a person might encounter on a first or second date, without ever having to go on one. As David Yarus, a recent graduate of Babson College, outside Boston, puts it: "Facebook has taken the potentially awkward first stages of flirting and getting to know someone into the comfort of your own home. "A. It's easier to approach each other, to talk casually, to get to know one another and feel out romantic potential without ever having to truly put themselves out there.B. "And you don't even have to be on the computer to engage in it. "C. They can see where that person grew up, their political interests, whether they're "looking for a relationship" or only interested in" hooking up. "D. As the thinking went, if you had to go to the Web to find a mate, or break up with one, it must have meant you weren't capable of attracting anyone in the real world.E. Now a relationship may still begin by locking eyes across a crowded bar, but instead of asking for a phone number, the next step almost surely involves a Facebook friendship offer.F. David Hein zinger, a 24 - year - old new - media specialist in New York. recently asked a girl he met at a happy hour to dinner.

填空题Development in Newspaper Organization One of the most important developments in newspaper organization during the first part of the twentieth century 1 , which are known as wire services. Wire service companies employed reporters, who covered stories all over the world. Their news reports were sent to papers throughout the country by telegraph. The papers paid an annual fee for this service. Wire services continue 2 . Today the major wire services are the Associated Press (AP) and United Press International (UPI). You will frequently find AP or UPI at the beginning of a news story. Newspaper chains and mergers began to appear in the early 1900s. A chain consists of two or more newspapers 3 . A merger involves combining two or more papers into one. During the nineteenth century many cities had more than one competitive independent paper. Today in most cities there are only one or two newspapers, and 4 . Often newspapers in several cities belong to one chain. Papers have combined 5 . Chains and mergers have cut down production costs and brought the advantages of big-business methods to the newspaper industry. A. to play an important role in newspaper operations B. was the growth of telegraph services C. and they usually enjoy great prestige D. they are usually operated by a single owner E. in order to survive under the pressure of rising costs F. owned by a single person or organization

填空题A. merging the regulatory operations of NASD and NYSEB. for the construction industry, schools and housesC. to shrink the cabinetD. as too little, too late to help Germany out of a recessionE. as a tough female leaderF. reducing costly duplications

填空题A. Significance of Testing Techniques for Sampling Microbes in the Deep Ice SheetB. Special Features of Lake VidaC. Later Expedition on MarsD. 2004 Revisit Planned for Collecting Lake Water SpecimensE. Antarctic Frozen Life Sampled and RevivedF. Accidental Discovery of Ice-sealed Lake Water in Antarctica

填空题3. California University Cuts Protested Thousands of students, faculty members and employees at the 10 University of California campuses protested budget cuts, unpaid faculty furloughs (休假) and tuition increases on Thursday. Officials at the University of California, Berkeley, estimated that several thousand protesters were in Sproul Plaza chanting and waving signs. (46) Other campuses reported smaller turnouts (聚集的人群) at rallies (集会) and marches. "Everyone agrees there is a budget crisis and that the university must respond," said Joshua Clover, an associate professor of English at U. C. Davis who was a co - author of a petition (情愿书) calling for the faculty walkout on Thursday. Mr. Clover said (47) The online walkout petition was signed by 1,221 of the 19,000 faculty members statewide. A union representing more than 11,000 university professional and technical staff members supported the protest and called a one -day strike. (48) The university' s budget now stands at $ 2. 6 billion. Friction (摩擦) has developed between the administration and some faculty and staff members and students over how and where to cut. Among the more contentious (有异议的) items are a proposed 32 percent increase in student tuition by fall 2010, and decisions made by the university president, Mark Yudof, over how to handle mandatory (义务性质的) faculty furlough days, which will reduce pay by 4 to 10 percent. (49) "I chose Berkeley over all the other universities because it offered me a very good education at a price my family could afford," said Brandon Pham, 17, a freshman political science major who skipped the day' s classes in protest. Mr. Pham held a sign that read:" We make the university. They make the crisis. " Steve Montiel, a spokesman for the University of Califomia' s office of the president, said, (50) A. "We respect people expressing themselves, but we hope they realize that the true source of their frustration is in Sacramento at the state capital. "B. The Legislature approved a reduction of $ 637.1 million, about 20 percent of the university' s 2009 -2010 fiscal year (财政年度) financing, as part of the budget agreement reached in August.C. "The problem is that the administration' s handling of the budget cuts disproportionately (不成比例) harms those who can least afford it both among the workers and the students. "D. Average yearly tuition and fees for undergraduates this academic year are $ 8,720.E. Most academic departments on campus reported that some classes had been canceled because faculty members and students walked out.F. Still, many students at Berkeley did not participate in the protest and walked about campus as they would on any other Thursday.

填空题 Understanding Autism 1. Autism (孤独症) is a life-long developmental disability that prevents individuals from properly understanding what they see, hear, and otherwise sense. This results in severe problems of social relationships, communication, and behavior. Individuals with autism have to painstakingly (费力地) learn normal patterns of speech and communication, and appropriate ways to relate to people, objects, and events, in a similar manner to those who have had a stroke. 2. The cause of autism is still unknown. Some research suggests a physical problem affecting those parts of the brain that process language and information coming in from the senses. There may be some imbalance of certain chemicals in the brain. Genetic (遗传的) factors may sometimes be involved. Autism may indeed result from a combination of several "causes". 3. Most people with mental retardation (智力迟钝的) show relatively even skill development. Individuals with autism, however, typically show uneven skill development, with deficits (欠缺) in certain areas—most frequently in their ability to communicate and relate to others—and distinct skills in other areas. It is important to distinguish autism from mental retardation or other disorders, since diagnostic (诊断的) confusion may lead to inappropriate and ineffective treatment techniques. 4. In general, individuals with autism perform best at jobs which are structured and involve a degree of repetition. Some people who have autism are working as artists, piano tuners, painters, farm workers, office workers, computer operators, dishwashers, assembly line workers, or employees of sheltered workshops or other sheltered work settings.

填空题Exercising Your Memory 1 Aging does not mean a dramatic decline in memory power, unless you help it happen by letting your mind go. 2 That"s not to say that memory doesn"t change throughout life. Researchers divide memory into categories based on the length of time when memories are stored. One system divides it up as short-term (less than one minute; remembering a telephone number while you dial, for instance), long-term (over a period of years) and very long-term memory (over a lifetime). 3 Short-term memory isn"t mastered until about age 7, but after that you never lose it. Long-term memory, however, involves more effort and skill and changes more through life. It"s not until the early teens (十几见闻) that most people develop a mature long-term memory. 4 First, we must get information into our heads through learning. Learning strategies can get rusty (生锈) without constant use. High school and college students, who are forced to repeatedly exercise their long-term memory abilities (at least long-term enough to get them through a final exam ), usually do well on memory tests. The longer you stay in school, the more chance you get to polish your learning skills. It"s no wonder that more highly educated people have more effective memory skills throughout life. 5 Although older people in general learn somewhat more slowly than they did when younger, a dramatic difference exists between those who stay intellectually active—reading, discussing, taking classes, thinking—and those who do not. Giving the brain daily workout (锻炼) is just as important as exercising your muscles. Brainwork keeps your learning strategies in shape, and this helps your memory to function at full capacity. 6 The next part of a healthy long-term memory is retention (记忆力), the ability to store what you have learned. Memory researchers still do not know whether memories are lost—whether they still exist in the brain but our mental searching cannot turn them up, or have disappeared entirely as our brain ages. 7 The third necessity for memory is recall, the ability to bring to mind the memories we have stored. Again, while aging has widely different effects on the recall abilities of different people, research indicates that the older we get, the longer it takes to recall facts. But slower recall is still recall. In fact, aging does not seem to have any effect on forgetting at all, which takes place at the same rate in younger and older people.

填空题Sleep Well to Be Well 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. 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. 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. 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.

填空题The Invader of AIDS The invader is small, even in the microscopic world of bacteria and viruses. It is alive only in the strictest sense of the world. It had no intelligence, no means of mobility, and no methods of defense in the outside world. It is fragile, easily killed by common household bleach (漂白剂) and even short periods outside the body. 1 It is the AIDS virus, and it is a killer. AIDS is a disease, caused by a virus that breaks down part of the body"s immune system, leaving a person defenseless against a variety of unusual life-threatening illnesses. 2 The body"s immune system normally provides us the weapons we need to win constant battles with invading viruses, bacteria and other invading organisms. His defense system is powerful but not perfect. 3 We do not even know that anything is happening. But the AIDS virus acts differently from other invaders. It attacks the very cells that normally protect us. 4 It turns our own white blood cells into mini-factories or making more viruses. Each time a cell is taken over, it fills up with thousands of new viruses, dies and releases those viruses which attack more white blood cells. After enough attacks, our defense system is weakened and certain infections and conditions that we normally fight off with no problem take advantage of his weakness. 5 The person dies. There is no cure for AIDS, so learning about the disease and how to avoid it are our only weapons. A. Yet it may be the most dangerous enemy in human history. B. Whatever condition develops because of AIDS, the outcome is always the same. C. It gets inside these cells. D. Each of the letters in AIDS stands for a word: Acquired Immune Deficiency Syndrome. E. The patients who suffer from AIDS have characteristic features. F. Most attacks are detected and beaten off with ease.

填空题 {{B}}Bomb Explosions in Thailand{{/B}} The new year celebration in Thailand was shattered by violence, when nine bombs exploded across Bangkok around midnight. Three Thai citizens were killed and more than 30 injured. Among the injured, six were foreigners. No Chinese casualties were reposed, the Chinese Embassy in Bangkok, the capital, said on Monday. {{U}} {{U}} 1 {{/U}} {{/U}}But other embassies have advised their citizens to avoid traveling to Bangkok. "There is a possibility of further attacks in coming days," said a travel advisory (公告) from Australia. "Australians are urged to avoid unnecessary travel in Bangkok." No terrorist group claimed responsibility for the bombings by Tuesday. {{U}} {{U}} 2 {{/U}} {{/U}}Bombings and shootings occur almost daily in Thailand's three southernmost provinces. Yala, Naarathiwat and Pattani have a dominant Muslim population and have long complained of neglect (忽视) and discrimination (歧视) in the largely Buddhist (佛教徒的) nation. They have asked for independence and a separate Islamic (伊斯兰的) state. Since 2004, the insurgents (叛乱者) have carried out numerous attacks in the south and more than 1,900 people have been killed. {{U}} {{U}} 3 {{/U}} {{/U}} But Thai Prime Minister Surayud Chulanont said on Monday that domestic politics rather than the Muslim insurgency was behind the bombings. "It is likely related to people who lost their political benefits," Surayud said, referring to Thaksin Shinawatra. {{U}} {{U}} 4 {{/U}} {{/U}}Surayud was later appointed interim (临时的) prime minister. Thaksin, however, still enjoys widespread support, especially in the countryside. {{U}} {{U}} 5 {{/U}} {{/U}}Thaksin's lawyer, Noppadol Patama, denied his client's involvement in the bombings, according to a local website. A. Some believe the explosions were the work of Muslim separatists. B. Some believe that several senior army officers loyal to Thaksin plotted the bombings with ousted (赶下台) politicians to discredit (败坏名声) the government. C. Thaksin was ousted in a military coup (政变) last September. D. The Thai Government has been unable to control the violence, though thousands of troops have been sent to the south. E. The embassy issued no travel warnings. F. Nobody is to blame.

填空题 The First Four Minutes When do people decide whether or not they want to become friends? During their first four minutes together, according to a book by Dr. Leonard Zunin. In his book, Contact. The first four minutes, he offers this advice to anyone interested in starting new friendships: {{U}} {{U}} 1 {{/U}} {{/U}}A lot of people's whole lives would change if they did just that. You may have noticed that average person does not give his undivided attention to someone he as just met. {{U}} {{U}} 2 {{/U}} {{/U}}If anyone has ever done this to you, you probably did not like him very much. When we are introduced to new people, the author suggests, we should try to appear friendly and self-confident. In general, he says, "People like people who like themselves." On the other hand, we should not make the other person think we are too sure of ourselves. It is important to appear interested and sympathetic, realizing that the other person has his won needs, fears, and hopes. Hearing such advice, one might say, "But I'm not a friendly, self-confident person. That's not my nature. It would be dishonest for me to act that way." {{U}} {{U}} 3 {{/U}} {{/U}}We can become accustomed to any changes we choose to make in our personality. "It is like getting used to a new car. It may be unfamiliar at first, but it goes much better than the old one." But isn't it dishonest to give the appearance of friendly self-confidence when we don't actually feel that way? Perhaps, but according to Dr. Zunin, "total honest" is not always good for social relationships, especially during the first few minutes of contact. There is a time for everything, and a certain amount of play-acting may be best for the first few minutes of contact with a stranger. That is not the time to complain about one's health or to mention faults one finds in other people. It is not the time to tell the whole truth about one's opinions and impressions. {{U}} {{U}} 4 {{/U}} {{/U}}For a husband and wife or a parent and child, problems often arise during their first four minutes together after they have been apart. Dr. Zunin suggests that these first few minutes together be treated with care. If there are unpleasant matters to be discussed, they should be dealt with later. The author says that interpersonal relations should be taught as a required course in every school, along with reading, writing, and mathematics. {{U}} {{U}} 5 {{/U}} {{/U}}That is at least as important as how much we know. A. In reply, Dr. Zunin would claim that a little practice can help us feel comfortable about changing our social habits. B. Much of what has been said about strangers also applies to relationships with family members and friends. C. In his opinion, success in life depends mainly on how we get along with other people. D. Every time you meet someone in a social situation, give him your undivided attention for four minutes. E. He keeps looking over the other person's shoulder, as if hoping to find someone more interesting in another part of the room. F. He is eager to make friends with everyone.

填空题"I smoke for my health," I declared in a newspaper article published in 1979. (46) . I reasoned that smoking made me cough and thus prevented pneumonia (肺炎); smoking made my heart go faster and eliminated the need for special exercise; smoking restrained my appetite and kept me trim. And then, at 51, I had a heart attack. I knew the risk factors for early heart attacks include hypertension, diabetes(糖尿病), and a family history of heart disease, high blood-cholesterol (胆固醇)levels and smoking. (47) . Strange how the evidence that linked smoking to heart disease appeared unclear to me, and how the same data now appear overwhelmingly convincing. Why stop now? Smokers who stop after their first heart attack have an 80-percent chance of living ten more years-- (48) . As a smoker, I always resented the fact that we smokers received only scorn from non-smokers. How could non-smokers know that smoking was had for the health if there were no smokers to prove it? Being a member of the experimental group, rather than the control group, deserves a certain measure of social appreciation. I've done my time. I' m now ready to be a control. I no longer smoke for my health. My health can' t stand the help. Will I miss the late - night trips to find a store that's still open and selling cigarettes? Will I miss searching through ashtrays(烟灰缸)to find the longest butt(烟蒂) that is still smokable? Only time will tell. Not smoking may give me the time to find out. (49) Sure. Here is all you have to do. First, experience a severe crushing pain under your breastbone as you finish a cigarette. Next, have yourself admitted to a coronary-care(心脏康复)unit and be stripped of your clothing and belongings. Finally, remain in the unit at absolute bed rest for four days while smoking is forbidden. This broke my habit (50) A. Was it easy to stop?B. if they don't, a 60 percent chance.C. See if it works for you.D. All the smokers find it's hard to stop.E. Since I am a doctor, this advice attracted amused attention.F. The first four were in my favour, but I chose to smok

填空题Organ Donation and Transplantation 1 Organ donation and transplantation refers to the process by which organs or tissues from one person are put into another person's body. 2 The number of people needing a transplant continues to rise faster than the number of donors. About 3,700 transplant candidates are added to the national waiting list each month. Each day, about 77 people receive organ transplants. However, about 18 people die each day waiting for transplants that can't take place because of the shortage of donated organs. 3 There are no age limits on who can be an organ donor. Newborns as well as senior citizens have been organ donors. If you are younger than 18, you must have a parent's or guardian's consent. If you are 18 years or older, you can show you want to be an organ and tissue donor by signing a donor card. 4 Many people think that if they agree to donate their organs, the doctor or the emergency room staff won't work as hard to save their life. This is not true. The transplant team is completely separate from the medical staff working to save your life. The transplant team does not become involved with you until doctors have determined that all possible efforts to save your life have failed. 5 If you need an organ transplant, your doctor will help you get on the national waiting list. Your name will become part of a pool of names. When an organ donor becomes available, all the patients in the pool are compared to the donor. Factors such as blood and tissue type, size of the organ, medical urgency of the patient's illness, time already spent on the waiting list, and distance between donor and recipient are considered.A. Quality of donated organB. Benefits of organ donationC. Distribution of donated organsD. Quality of donor medical careE. Age limits of organ donationF. Status of organ donation and transplantation

填空题A. is found to be a great deal higher than that of seawaterB. was of little scientific valueC. may be older than that collected below 39 feet of iceD. might have come from MarsE. is to collect some briny lake water for analysisF. may return to life sooner than microbes frozen in the surface ice

填空题A. than more recent onesB. the killing efficiency for older eruptionsC. has remained controversialD. Wignall's calculations as acceptableE. has been mown to us allF. his ideas

填空题A. if there isn't enough dopamine m your bodyB. what affects muscles all through your bodyC. which cannot be cured yetD. if you have a fixed or blank expressionE. which may be the first symptom you noticeF. what causes Parkinson's disease

填空题Exercising Your Memory 1. Aging does not mean a dramatic decline in memory power, unless you help it happen by letting your mind go. 2. That"s not to say that memory doesn"t change throughout life. Researchers divide memory into categories based on the length of time when memories are stored. One system divides it up as short-term (less than one minute; remembering a telephone number while you dial, for instance) , long-term (over a period of years) and very long-term memory (over a lifetime). 3. Short-term memory isn"t mastered until about age 7, but after that you never lose it. Long-term memory, however, involves more effort and skill and changes more through life. It"s not until the early teens (十几岁) that most people develop a mature long-term memory. 4. First, we must get information into our heads through learning. Learning strategies can get rusty (生锈) without constant use. High school and college students, who are forced to repeatedly exercise their long-term memory abilities (at least long-tern1 enough to get them through a final exam), usually do well on memory tests. The longer you stay in school, the more chance you get to polish your learning skills. It"s no wonder that more highly educated people have more effective memory skills throughout life. 5. Although older people in general learn somewhat more slowly than they did when younger, a dramatic difference exists between those who stay intellectually active—reading, discussing, taking classes, thinking — and those who do not. Giving the brain daily workout (锻炼) is just as important as exercising your muscles. Brainwork keeps your learning strategies in shape, and this helps your memory to function at full capacity. 6. The next part of a healthy long-term memory is retention (记忆力), the ability to store what you have learned. Memory researchers still do not know whether memories are lost—whether they still exist in the brain but our mental searching cannot turn them up, or have disappeared entirely as our brain ages. 7. The third necessity for memory is recall, the ability to bring to mind the memories we have stored. Again, while aging has widely different effects on the recall abilities of different people, research indicates that the older we get, the longer it takes to recall facts But slower recall is still recall. In fact, aging does not seem to have any effect on forgetting at all, which takes place at the same rate in younger and older people.

填空题More Than 8 Hours Sleep Too Much of a Good Thing 1 Although the dangers of too little sleep are Widely known, new research suggests that people who sleep too much may also suffer the consequences. 2 Investigators at the University of California in San Diego found that people who clock up 9 or 10 hours each weeknight appear to have more trouble falling and staying asleep, as well as a number of other sleep problems, than people who sleep 8 hours a night. People who slept only 7 hours each night also said they had more trouble falling asleep arid feeling refreshed after a night's sleep than 8-hour sleepers. 3 These findings, which Dr. Daniel Kripke reported in the journal Psychosomatic Medicine, demonstrate that people who want to get a good night's rest may not need to set aside more than 8 hours a night. He added that "it might be a good idea" for people who sleep more than 8 hours each night to consider reducing the amount of time they spend in bed, but cautioned that more research is needed to confirm this. 4 Previous studies have shown the potential dangers of chronic shortages of sleep, for instance, one report demonstrated that people who habitually sleep less than 7 hours each night have a higher risk of dying within a fixed period than people who sleep more. 5 For the current report, Kripke reviewed the responses of 1,004 adults to sleep questionnaires, in which participants indicated how much they slept during the week and whether they experienced any sleep problems. Sleep problems included waking in the middle of the night, arising early in the morning and being unable to fall hack to sleep, and having fatigue interfere with day-to-day functioning. 6 Kripke found that people who slept between 9 and 10 hours each night were more likely to report experiencing each sleep problem than people who slept 8 hours. In an interview, Kripke noted that long sleepers may struggle to get rest at night simply because they spend too much time in bed. As evidence, he added that one way to help insomnia is to spend less time in bad. "It stands to reason that if a person spends too long a time in bed, then they'll spend a higher percentage of time awake," he said.A. Kripke's Research ToolB. Dangers of Habitual Shortages of SleepC. Criticism on Kripke's ReportD. A Way of Overcoming InsomniaE. Sleep Problems of Long and Shoat SleepersF. Classification of Sleep Problems

填空题 Cars Are Good for the Environment Britain's motor industry is planning a major publicity campaign to counter what it sees as an official anti-car bias and to improve, the environmental image of the cars, according to documents leaked to the pressure group, Friends of the Earth (FOE). (46) . The internal document which was produced last month by the Society of Motor Manufacturers and Traders, says that the "ultimate objective of the campaign must be to protect the long term commercial freedom of the motor industry and the lifestyle freedom of car users". (47) . European car manufacturers have already agreed with the European Commission to reduce CO2 emissions from new cars by 25 per cent to target of 140 grams per kilometre by 2008. However, the document also reveals that the industry is some way from meeting the target. (48) . To help control these emissions, the government has proposed replacing the flat rate annual tax on cars with a tax related to engine size so that owners of large gas-guzzler(耗油量大的汽车)would pay more than owners of small cars. (49) . Richard Barnet, the society's media manager, says:"We will work with the government to practise a practical system." (50 .A The campaign will highlight the motor industry's efforts to reduce emissions of carbon dioxide(二氧化碳)B But the motor industry opposes taxes on persons owning cars preferring taxes on useC The five-year campaign could cost up to ￡12 millionD The reason why cars are good for the environment is obviousE But Ian Willmore of FOE says the industry "may pose as partners of the government, but its real intention is to frustrate serious attempts to reduce traffic levels"F For example, last year's new cars exceed an average of 192 grams per kilometre —some 37 percent above the target

填空题Cancer Cancer is a group of many related diseases that begin in cells, the body"s basic building blocks. The body is made up of many types of cells. Normally cells grow and divide to produce more cells as they are needed to keep the body healthy. Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. The extra cells form a mass of tissue called a growth or tumor. Benign (良性的) tumors are not cancer. They can often be removed and, in most cases, they do not come back. Malignant (恶性的) tumors are cancer. Cells in malignant tumors are abnormal and divide without control or order. Scientists have learned that cancer is caused by changes in genes that normally control the growth and death of cells. Certain lifestyle and environmental factors can change some normal genes into genes that allow the growth of cancer. Many gene changes that lead to cancer are the result of tobacco use, diet, exposure to ultraviolet radiation from the sun, or exposure to carcinogens (致癌物) in the workplace or in the environment. Some gene alterations are inherited. Cancer treatment can include surgery, radiation therapy, chemotherapy (化疗), hormone therapy, and biological therapy. The doctor may use one method or a combination of methods, depending on the type and location of the cancer, whether the disease has spread, the patient"s age and general health, and other factors. Because treatment for cancer can also damage healthy cells and tissues, it often causes side effects. Patients and doctors generally discuss the treatment options, weighing the likely benefits of killing cancer cells and the risks of possible side effects. Having cancer does not always mean having pain. Whether a patient has pain may depend on the type of cancer, the extent of the disease, and the patient"s tolerance for pain. Most pain occurs when the cancer grows and presses against bones, organs, or nerves. Pain may also be a side effect of treatment. However, pain can generally be relieved or reduced with prescription medicines or over-the-counter drugs recommended by the doctor.