最新Writing-explanations英语说明文

最新Writing-explanations英语说明⽂
Lesson 12 Writing explanations (causes and effects)
Part I What are explanations?
1.Explanations are about causes and effects of a phenomenon.
2.Explanations are of four general types: they may consist of a simple sequence of causes and
effects; a sequential explanation; they may involve multiple causes, a factorial explanation, or multiple effects, a consequential explanation; or the effects may vary depending on variable conditions, a conditional explanation.
3.In an explanation, logical relations between events are often shown by transition words and
phrases, such as ‘because, so, therefore’, ‘if…then’, or ‘however, but, nevertheless’, and so on.
4.In written explanations, causal (有因果关系的) relations need not be made explicit (明确的，清
楚的). That is, the ca usality may not be explicitly realised as causal conjunctions like ‘because, so, therefore’, but can be implicit (不⾔明的，含蓄的) in the explanation genre. The genre is typically announced in the phenomenon stage, so the reader can infer (推断，推定) causal relations where they are not stated.
Part II Four types of explanation
1. Factorial explanations
Factorial explanations discuss the factors for a phenomenon to exist.
Stages: phenomenon + factor 1 + factor 2 + factor 3 + …
Sample 1: Causes of environmental pollution
Several factors can account for environmental pollution. The first and foremost factor leading to pollution is industrial production. This includes excavating fossils and raw materials from the depths of the planet, as well as their further refinement, and emissions from factories and energy plants such as carbon monoxide, hydrocarbons, and organic compounds. Farming and timber production are the second major reason why pollution keeps spreading around the planet. The modern agricultural sector consumes vast amounts of resources, at the same time producing tons of waste. For example, in order to grow cereal and other plants, extremely harmful fertilizers are being used widely. These chemicals affect the environment, as well as human health, in a negative way. In addition, timber production causes global deforestation, and this leads directly to the increase of the carbon dioxide share in the atmosphere. Yet another factor of environmental pollution is what is usually called household chemicals. Many people unconsciously contribute to massive atmosphere pollution without even knowing it. Fumigating homes, household cleaning products or painting supplies, insect and pest repellents, refrigerator liquids, deodorants, hairspray, and other similar products pollute air every day.
Questions: What is the phenomenon? What are the factors leading to the phenomenon? What transitions are used? What words and expressions are used to show the causality? What is one problem with the paragraph?
2. Consequential explanations
Consequential explanations discuss the results/effects/consequences of a phenomenon. A single event/phenomenon may lead to several consequences in the natural world.
Stages: phenomenon + result 1 + result 2 + result 3 + …
Sample 2: Essay: Stresses of Being a Celebrity
Last week, a woman signing herself “Want the Truth” wrote to Ann Landers with a question she just had to have answered.“Please find out for sure,” she begged the columnist, “whether or not
Oprah Winfrey has had a face-lift.” Fortunately for Ms. Winfrey’s privacy, Ann Landers refused to answer the question. But the incident disturbed me. How awful it would be to be a celebrity, I thought, and always be in the public eye. Celebrities lead very stressful lives, for no matter how glamorous or powerful they are, they have too little privacy, too much pressure, and no safety.
For one thing, celebrities do not have the privacy an ordinary person has. The most personal details of their lives are
splashed all over the front pages of newspapers and magazines so that people can read about “Roseanne and Her New Love” or “Letterman’s Deepest Fear.” Even a celebrity’s family is hauled into the spotlight. A teenage son’s arrest for pot possession or a wife’s drinking problem becomes the subject of glaring headlines. Photographers hound celebrities at their homes, in the restaurant, and on the street, hoping to get a picture of a Cindy Crawford in curlers or a Bruce Willis guzzling a beer. When celebrities try to do the things that normal people do, like eating out or attending a football game, they run the risk of being interrupted by thoughtless autograph hounds or mobbed by aggressive fans.
In addition, celebrities are under endless pressure. Their physical appearance is always under observation. Famous women, especially, suffer from the “she really looks old” or “boy, has she put on weight” spotlight. Unflattering pictures of celebrities are photographers’ prizes to be sold to the highest bidder; this increases the pressure on celebrities to look good at all times. Famous people are also under pressure to act calm and collected under any circumstances. There’s no freedom to blow off steam or to do something just a little crazy. Therefore, people who forget this must suffer the consequences.
Most important, celebrities must deal with the stress of being in constant danger. The friendly grabs, hugs, and kisses of enthusiastic fans can quickly turn into uncontrolled assaults on a celebrity’s hair, clothes, and car. Celebrities often get strange letters from people who become obsessed with their idols or from people who threaten to harm them. Worst of all, threats can turn into deeds. The attempt to kill Ronald Reagan and the murder of John Lennon came about because two unbalanced people tried to transfer the celebrity’s fame to themselves. Famous people must live with the fact that they are always fair game—and never out of season.
Some people dream of starring roles, their names in lights, and their pictures on the cover of People (“⼈物”杂志) magazine. I’m not one of them, though. A famous person gives up private life, feels pressured all the time, and is never completely safe. So let someone else have that cover story. I’d rather lead an ordinary, but calm, life than a stress-filled public one.
columnist专栏作家facelift ⾯部整形⼿术glamorous充满魅⼒的
splash以显著地位刊登pot【俚语】⼤⿇glaring耀眼的
hound v. 追逐 curler卷发夹⼦autograph 亲笔签名
guzzle狂饮, 暴⾷mob 聚众滋扰collected 冷静的, 镇定的
blow off steam发脾⽓obsess 被缠住/烦扰unbalanced 不稳定的;精神错乱的
fair game准许捕猎的猎物, 可攻击的对象
Questions：
1.About coherence: What are the main transitions in the body?
2.What method of introduction is used?
a. Broad, general statement narrowing to thesis
b. Opposite
c. Quotation
d. Anecdote
e. Questions
3. Sequential explanations
Sequential explanations are typically constructed as a series/sequence of events, in which an obligatory causal relation is implied between each event.
Stages: cause 1 + effect 1(cause 2) + effect 2(cause 3) + effect 3 (cause 4) + …
Sample 3:
4. Conditional explanations
In conditional explanations, effects may vary depending on variable conditions or factors.
Conditional explanations are found across all technical fields in varying forms.
Different conditions lead to different results/effects: If A, then B; If C, then D; If E, then F. Sample 4: Predator (捕⾷者) and
prey (被捕⾷者) population numbers
Population size of one species can be affected by the size of the population of another species. This is true in the case of a predator species and the prey species on which it feeds. Over time, several outcomes are possible. If the predators are absent, the prey population will increase exponentially (迅速增长地) but will eventually ‘crash’ when its numbe rs become too high to be supported by the food resources in the habitat. If the prey population is too small, the predator population will starve and die. In some cases, cycles of ‘boom-and-bust’ can be seen in both populations, with the peak in the predator population occurring after the peak in the prey population. Why?
Questions:
Why is this text a conditional explanation? What are the conditions and what are the results? What special expressions are used in conditional explanations?
Sample 5：Buoyancy (浮⼒) and Density (⽐重，密度)
If the object is completely submerged, it displaces (排⽔) its own volume of fluid. The weight of displaced fluid, and therefore the upthrust (浮⼒), will depend on the density of the fluid.
If the density of the fluid is less than the average density of the object, the weight of the displaced fluid will be less than the weight of the object and the object will sink.
If, on the other hand, the density of the fluid is greater than the average density of the object, the weight of the displaced fluid will therefore exceed the weight of the object. The net upward force will then cause the object to rise to the surface where it will float.
Questions: How many conditions are there? What are the results?
Part III Expressions
A contributes to
B (A causes B)
…attribute A to B (B causes A)
…ascribe (把…归因于) A to B: (B causes A) give rise to /generate
This is the reason why…
with reason that…/for the reason that…
the cause of…/ the cause for…
reason for/by reason of…
owe A to B (B is the reason for A)
owing to/ due to /because of
accordingly; therefore; hence; thus; consequently why…is because/that…
Homework assignment: (Due in Week 13)
Directions: Write two explanations: one is factorial, the other consequential.
1)Causes of students’ sleep deprivation (睡眠不⾜)
2)Consequences of procrastination (拖延)。