托福写作7、8课(四)

例子：网络故事书（web－storybook service）
　　reading网络故事书的好处
　　1.可以教小朋友读书
　　2.经济实惠，家长不需要为孩子买书了
　　3.可以代替父母陪伴孩子，为家长节省时间
　　lecture反驳
　　1.使用时不能和小朋友互动（ask question and get feedback）
　　2.网络上的故事都是过时的，要想读新故事还是要买书（不足）
　　3.父母与孩子一起读书可以增进感情
　　例文：
　　The speaker rebuts the reading's argument by pointing out the inadequacy of the web-storybook services' interaction with children, the incompleteness of the data pool, and by undermining the assumption that saving parents' reading time is a benefit.
　　The speaker begins by stating that merely pronouncing the words and story for the children will not provide adequate learning experiences. Despite the time saved and pronunciation utilities laid out in the reading, the web services can only respond with "correct" or "not correct". The lack of feedback to children's questions will not create an effective learning process.
　　Then the speaker goes on to argue that the current web-storybook services have a very limited collection of books, thus not being able to save parents the cost of new books as the reading states, because the parents still have to buy many books that the web services do not provide.
　　Lastly, the speaker challenges the validity of the assumption of saving parents' time to read stories to children. The reading argues that saving the time is a benefit for the parents, but the speaker maintains that the whole point of reading stories is far beyond reading stories alone. In contrast, it is an essential way of communicating and building relationship between parents and children.
　　例子：网络问卷（web based survey）
　　reading网络问卷相对传统问卷的优势
　　1 调查范围广，结果就更为准确
　　2 发放，填写和收集问卷更加方便简单
　　3 成本低
　　lecture反驳网络问卷的优势
　　1 调查结果不全面因为不是所有人都会上网，中老年人上网会比较少
　　2 成本并不会低，因为一个好的网络问卷需要一个团队的大量工作（提出新的证据：网络问卷也需要成本和人力资源
　　3大多数人对网络问卷不严肃，得到不正确的信息，容易混淆视听。
　　例文：
　　The speaker questions the effectiveness of web based surveys by providing evidences contradictory to the reading.
　　First, he identified the reading's logical flaw in assuming that an increase in the scope and quantity of the survey will automatically translate to greater precision of the surveys. However, if surveys aim to question people over 60 years old, how can these old people conduct surveys online since this group seldom surf the Internet? The web surveys are effective in reaching mainly the young generation. Thus the results cannot be extended to demonstrate the views of the whole population.
　　Second, although the web-based surveys will lower paper cost, they will inevitably incur new costs in web designing, flashy features, and other elements, which will require more costly team work. This evidence effectively attacks the reading's argument that web surveys will certainly reduce the cost of the survey.
　　In the end, many web designers tend to overdo in the webpage and add fancy and flashy features. As a result, many people perceive the web-based surveys as not serious and are thus not willing to respond to the surveys. Unlike physical surveys that draw attention effectively, many web based surveys are simply ignored or even deleted.

例子：加氟自来水（adding fluoride in public water）
　　reading在自来水中加氟的好处
　　1 防止蛀牙
　　2 杀死细菌
　　3 对骨骼有好处（decrease bone diseases）
　　lecture反驳
　　1 自来水并不会留在口中，对防止蛀牙没有帮助
　　2 氟会与输水管中化学物质反应，产生有毒物质，其危害大于细菌
　　3 过量的氟会使骨骼变脆
　　例文：
　　The speaker refutes the reading's argument about the benefits of adding fluoride to pipe water by providing contradictory evidence about pipe water's fluoride's effectiveness in preventing cavities in teeth, killing bacteria, and decreasing bone diseases.
　　First, the speaker points out that the short contact of fluoride with teeth will not enable the fluoride to prevent cavities, as the reading argues. Instead, the water will pass the mouth and teeth quickly and go directly to the stomach. Another argument raised in the lecture is that fluoride could undergo chemical reactions with heavy metals in the pipe, such as lead. This will create toxic substances which will pose serious health threat. In this way fluoride could be even more deadly than bacteria. Although the fluoride, as the reading says, will kill some bacteria, the cure here is worse than the disease.
　　In the end, the speaker maintains that overdose of fluoride will backfire to human bones. Although the reading illustrates that fluoride will improve bone strength, the lecture says overdose will cause serious damage to human bones.
　　Water fluoridation is the controlled addition of fluoride to a public water supply in order to reduce tooth decay.[1] Its use in the U.S. began in the 1940s, following studies of children in a region where water is naturally fluoridated; too much fluoridation causes dental fluorosis, which mottles or stains teeth, but U.S. researchers discovered that moderate fluoridation prevents cavities.[2] Water fluoridation has been contentious for ethical, safety, and efficacy reasons, and only about 5.7% of people worldwide drink fluoridated water.[3]
　　The history of water fluoridation can be divided into three periods. The first (c. 1901–33) was research into the cause of a form of mottled enamel called "Colorado brown stain", which later became known as fluorosis. The second (c. 1933–45) focused on the relationship between fluoride concentrations, fluorosis, and tooth decay. The third period, from 1945 on, focused on adding fluoride to community water supplies.[2]
　　Mechanism
　　Fluoride compounds are found naturally in the ground water in some regions, such as Colorado.[22]. Fluoridation chemicals are typically added to potable water in the form of sodium hexafluorosilicate or hexafluorosilicic acid (also known as hydrofluorosilic acid or fluorosilic acid).[23][24] This acid is largely a byproduct of phosporic acid磷酸 plants which process phosphate rock.[25] Since 2005, reduced phosphate processing has led to an increase in the price of fluorosilic acid, with one community seeing a 105% price increase in the past two years.[26]
　　[edit] Efficacy, effects, and cost-benefit analysis
　　When used appropriately, fluoride use is a safe and effective way to prevent and control dental caries蛀牙, and has contributed to dental health worldwide of both children and adults.[1] The recommended dosage of fluoride for humans from the CDC is 0.7 ppm to 1.2 ppm depending on the average maximum daily air temperature of the area. Fluoridation is intended to reduce tooth decay, with its associated health problems, at a low cost. Fluoridation of the public water supply is the "most equitable, cost-effective, and cost-saving method of delivering fluoride to the community." [27] In 2001, the US Centers for Disease Control and Prevention stated, "Although solid data on the cost-effectiveness of fluoride modalities alone and in combination are needed, this information is scarce."[1] A 1989 workshop on cost effectiveness of caries prevention concluded that water fluoridation is one of the few public health measures that saves more money than it costs to operate.[1] A 2000 comprehensive systematic review of the evidence stated that "it is surprising to find that little high quality research has been undertaken". The review found that fluoridation was associated with a decreased proportion of children with cavities (the range of mean decreases was 5% to 64%, the median 14.6%), and with a decrease in decayed, missing, and filled primary teeth (the range of mean decreases was 0.5 to 4.4 teeth, the median 2.25 teeth). It also found that at a fluoride level of 1 ppm an estimated 12.5% (range 7% to 21.5%) of people would have fluorosis they would find aesthetically concerning, and that there was no clear evidence of other adverse effects.[28]
　　[edit] Possible adverse health effects
　　Negative health effects are generally associated with fluoride intake levels above the commonly recommended dosage, which is accomplished by fluoridating the water at 0.7 – 1.2 mg/L (0.7 for hot climates, 1.2 in cool climates). This was based on the assumption that adults consumes 2 L of water per day,[29]:345 but may have a daily fluoride intake of between 1 – 3 mg/day, as men are recommended to drink 3 liters/day and women 2.2 liters/day.[30] In 1986 the United States Environmental Protection Agency (EPA) established a maximum contaminant level (MCL) for fluoride at a concentration of 4 milligrams per liter (mg/L), which is the legal limit of fluoride allowed in the water. In 2006, a 12-person committee of the US National Research Council (NRC) reviewed the health risks associated with fluoride consumption[29] and unanimously concluded that the maximum contaminant level of 4 mg/L should be lowered. The EPA has yet to act on the NRC's recommendation.[31][32] The limit was previously 1.4 – 2.4 mg/L, but it was raised to 4 mg/L in 1985.[33]