参加托福考试的学生，以*生和大学生为主力。对于这些类别的学科，有些比较熟悉，例如经济学中“钱”的概念(TPO 2 what is money?)，但同样是经济学中的内容，广告商所采取的说服顾客购买的策略(TPO 3 in order to sell more products, advertisers will try to make us believe that a product will meet our needs or desires perfectly, even if it is not true.)这一话题，则显得相对陌生。而实际上，Task 6中常常会出现广告营销策略、市场定位等相关的话题，如果学生对此有一定了解，必然会帮助学生对听力内容的理解，其他学科的内容也是如此。
【补充查阅】：
Selective breeding (also called artificial selection) is the process by which humans breed other animals and plants for particular traits. Typically, strains that are selectively bred are domesticated, and the breeding is normally done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties, cultigens, or cultivars. The offspring of two purebreed animals but of different breeds is called a crossbreed, and crossbred plants are called hybrids.
A cultivar is a plant or grouping of plants selected for desirable characteristics that can be maintained by propagation.
A cultigen (from the Latin cultus - cultivated, and gens - kind) is a plant that has been deliberately altered or selected by humans; it is the result of artificial selection.
Modern wheat varieties have short stems. Short stems are important because the application of high levels of chemical fertilizers would otherwise cause the stems to grow too high, resulting in lodging (collapse of the stems). Stem heights are also even, which is important for modern harvesting techniques.
【参考回答】：
In this lecture, the professor tries to use two example explain the notion of selective breeding. This term refers to the process by which humans breed plants for particular traits that are called as desirable features.
One example of this is wheat. In the past, when wheat reached its maturity and was ready to be harvested, some stains would collapse on the ground, resulting in lodging. People deliberately chose those with short stems and not collapsing as for next breeding to reduce the lodging rate.
The other example is peach. When it comes to choose which bunch of peaches could be used in next breeding process, people select those big ones over small ones and hope to get better yield.
单元型总分结构：即General topic → sub topic (detailed description)。例如TPO 1的Task 6, 讲婴儿的计算能力：
Scientists have learned some interesting things about the intellectual abilities of babies. They say there is evidence that babies as young as five month old can do basic arithmetic: that they can add.（首段头两句，非常清楚的表述了General topic是婴儿有计算能力）……the evidence is indirect because……so they devised an experiment where……（紧接着引出了sub topic, 做实验，后面就详述了这个实验是什么，以及这个实验如何说明婴儿有计算能力）
这类文章的分述细节通常是一个步骤详细的实验。
双元总分结构：即General topic → sub topic 1 (definition1+example1) → sub topic 2 (definition2+example2)。例如TPO 3的Task 6, 讲说服消费者购买某产品的策略：
In advertising, various strategies are used to persuade people to buy products……The strategies they use can be subtle, friendly forms of persuasion that are sometimes hard to recognize.（general topic, 看似友好地说服消费者购买的广告方式）
In a lot of ads, repetition is a key strategy.（sub topic 1, 重复）Research shows that repeated exposure to a message even something meaningless or untrue is enough to make people accept it or see it in a positive light.（对“重复”下定义）You’ve all seen the car commercials on TV……this guy is driving around a he keeps stopping to pick up different people……and each time, the narrator says plenty of room for friends, plenty of room for family, plenty of room for everybody. The same message is repeated several times in the course of the commercial. Now the car……is not a very big car at all. But you get the sense that it is pretty spacious. ……what usually happens is that when the statement plenty of room is repeated often enough, people are actually convinced that it is true.（这个冗长的例子无非就是说，汽车广告反复宣称空间大，而实际上空间则并不大，反复的次数多了，受众就觉得确实空间很大）
Another strategy they use is to get a celebrity to advertise a product, it turns out that we are more likely to accept an advertising claim made by somebody famous.（sub topic 2, 明星代言）接着的两句话都是重复这么做的好处。You might have a car commercial that features a well know race car driver. Now it may not be a very fast car, it could even be an in expensive vehicle with a low performance rating. But if a popular race car driver is shown driving it and saying I like my car’s fast. Then people will believe the car is impressive for its speed.（还是汽车广告，请赛车手给经济车型做广告，大家会相信这车真的很快）
双元立体总分结构：即General topic → sub topic 1 (suptopic1A: definition1A+example1A / suptopic1B: definition1B+example1B) → sub topic 2 (definition2+example2)。例如TPO 2的Task 6, 讲钱的概念：
So let’s talk about money. What is money? Well, typically, people think of coins and paper bills as money. But that is using a somewhat narrow definition of the term. A broad definition is this: money is anything that people can use to make purchases with. Since many things can be used to make purchases, money can have many different forms.（开篇明义，说明硬币和纸钞是钱的一种，但并不完全如此。可以用于购买的东西都可以称作钱，因此钱的形式有很多种。）
广州智美教育—官网
