托福考試是學術英語考試，檢驗考生是否具備在國外大學里學習的能力，從聽力單項來看，托福聽力只考察兩類內容,兩篇對話主要涉及學生和校內工作人員的交流溝通，四篇講座主要內容就是課堂教學。托福聽力Lecture其實就是濃縮的大學講課，內容幾乎涵蓋大學里所能涉及到的所有基礎性科目：生命科學，藝術文學，社會科學，自然科學等。

每篇lecture時長在五分鐘左右，后面緊跟六個問題，多數為單選題，也會有多選題，重聽題，排序題等。想要攻克lecture我們需要認真思考的問題之一就是：lecture結構特點是什么?換言之，老師最喜歡怎么展開一堂課?作為有過多年學生經歷的我們，最了解的莫過于課堂以及老師。回想一下老師講課一般都是什么流程?我們最熟悉的課堂流程是這樣的：開場引入topic ——分論點1：支持性細節——分論點2：支持性細節——分論點3：支持性細節——總結 簡而言之，托福聽力多數文章都是采用“總分總”的模式展開。需要注意的是分論點數量不確定，最后的“總”(課堂總結部分)有時候會被教授省略，也就是講完最后一個分論點全文就結束了。

下面我們結合TPO17 Lecture4分析一下托福聽力講座類的基本結構。

文本：Ok, now I want to talk about an animal that has a fascinating set of defense mechanisms. And that’s the octopus, one of the unusual creatures that live in the sea. The octopus is prey to many species, including humans, so how does it escape its predators?

課堂開始教授第一句話開篇點題，今天要講一種動物以及這種動物是如何逃脫天敵的，接著分論點一：

文本：Well, let me back up here a second. Anyone ever heard of Proteous? Proteus was a God in Greek mythology who could change form. He could make himself look like a lion or a stone or a tree, anything you wanted, and he could go through a whole series of changes very quickly. Well, the octopus is the real world version of Proteus. Just like Proteus, the octopus can go through all kinds of incredible transformations. And it does this in three ways: by changing color, by changing its texture, and by changing its size and shape. 圍繞專有名詞Proteus展開，重點強調了Proteus具有change form, transform 的能力。

分論點二：

文本：For me, the most fascinating transformation is when it changes its color. It’s a normal skin color, the one it generally presents, is either red or brown or even grey, and it ’s speckled with dark spots. But when it wants to blend in with its environment to hide from its enemies, it can take on the color of its immediate surroundings: the ocean floor, a rock, a piece of coral, whatever. Charles?

Student：Do we know how that works, I mean, how they change colors?

Professor ：Well, we know that the reaction that takes place is not chemical in nature. The color changes are executed by two different kinds of cells in the octopus ’ skin, mainly by color cells on the skin’s surface called chromatophores. Chromatophores consist of tiny sacks filled with color dye. There might be a couple hundred of these color sacks per square millimeter of the octopus ’ skin, and depending on the species, they can come in as many as five different colors. Each one of these sacks is controlled by muscles. If the muscles are relaxed, the sack shrinks, and all you see is a little white point. But if the muscle’s contract, then the sack expands, and you can see the colors. And by expanding different combinations.

Student: And just with various combinations of those five colors, they can recreate any color in their environment?

Professor: Well, they can no doubt create a lot with just those five colors, but you are right, maybe they can’t mimic every color around them, so that’s where the second kind of cell comes in. Just below the chromatophores is a layer of cells that reflect light from the environment, and these cells help the octopus create a precise match with the colors that surround them. The colors from the color sacks are supplemented with colors that are reflected from the environment, and that ’s how they are able to mimic colors with such precision. So, that’s how octopus mimic colors. 分論點二講解how to change color，重點強調了兩種細胞，一種叫做chromatophores,這種細胞controlled by muscles. 另外一種細胞能夠reflect light.

分論點三：

文本：But they don’t just mimic the colors in their environment; they can alos mimic the texture of objects in their environment. They have these little projections on their skin that allow them to resemble various textures. The projections are called papillae. If the octopus wants to have a rough texture, it raises the papillae. If it wants to have a smooth texture, it flattens out the papillae, so it can acquire a smooth texture to blend in with the sandy bottom of the sea. So the octopus has the ability to mimic both the color and the texture of its environment. And it’s truly amazing how well it can blend in with its surroundings. You can easily swim within a few feet of an octopus and never see it. 分論點三講解how to change texture, 引入專有名詞Papillae。

分論點四：

文本：Um, now there’s a third way that octopus can transform themselves to blend in with or mimic their environment, and that’s by changing their shape and size, well, at least their apparent size. The muscular system of the octopus enables it to be very flexible to assume all sorts of shapes and postures. So it can contract into the shape of a little round stone, and sit perfectly still on the seafloor. Or it can nestle up in the middle of a plant and take the shape of one of the leaves. Even Proteus would be impressed, I think. 分論點四講解how to change size and shape, 舉了stone 和 leaves的兩個例子，文章結束。

總結來看，這篇lecture結構如下：

(1)Topic: animal, octopus, escape predators

(2)Subtopic1： Proteus: change form, transform

(3)Subtopic2 ：color：chromatophores, controlled by muscles

(4)Subtopic3 ：texture：papillae

(5)Subtopic4：shape&size: eg. stone, leaves

為什么掌握lecture的結構特點如此重要?這是由lecture的題目設置特點決定的。第一，考察大結構和重點強調內容，不考小細節。 Lecture的結構特點很明確的展示出重點內容的出現位置：開篇點題處，每個段落的主題句(一般是段落的第一句話)，課堂總結處。翻譯一下就是，這些地方是考點!!!第二，細節題全部順序出題。換句話說，如果在第一個細節題的四個選項里出現了文章最后才強調的內容，果斷排除!

我們還是以TPO17 L4為例,來看一下lecture的論點和分論點是如何對應考題的。

第一題主旨大意題，對應文章開頭，教授開篇點題處。

(1)What is the lecture mainly about?

A:Different kinds of color vision in sea animals.

B:Differences in appearance between various species of octopus.

C:Ways that octopuses attract their prey.

D:Ways that octopuses protect themselves from predators.

第二題考察Proteus, 對應分論點一。

(2) Why does the professor first mention Proteus?

A:To explain how the octopus got its scientific name.

B:To introduce the octopus’ exceptional abilities.

C:To point out that the octopus played an important role in Greek mythology.

D:To provide an example of a mythological character that was part animal and part human.

第三題考察how to change color，對應分論點二。

(3)How does an octopus change color to match the colors in its environment? Click on 2 answers

A:By raising its papillae.

B:By releasing colored ink.

C:By reflecting light from its environment.

D:By contracting the muscles around its chromatophores.

第四題考察how to change texture部分，對應分論點三。

(4)What does the professor say about the function of the papillae?

A:They produce dye in different colors.

B:They propel the octopus through the water.

C:They change the texture of the octopus’ skin.

D:They help the octopus contract into a smaller shape.

第五題考察how to change size and shape 部分，對應分論點四。

(5)What two examples does the professor mention to describe the octopus’ ability to change its shape? Click on 2 answers

A:A small round stone

B: The leaves of a plant

C:A cloud of ink.

D:A piece of coral.

第六題重聽題。重聽部分聽到的是例子細節。老師上課為什么會舉例子呢?舉例子的目的當然是幫助同學們理解某個知識點，所以該題的答案是 illustrate a point 闡明觀點。

(6)Why does the professor say this

A:To point out an error.

B:To illustrate a point.

C:To propose an explanation.

D:To correct a misunderstanding.

總結一下，托福聽力lecture結構的大原則就是總分總，在這個大原則的基礎上，每位老師講課有小差異，每篇lecture有自己的小特點，例如有的教授喜歡舉例子，有的教授喜歡講理論，還有的教授喜歡做實驗，lecture結構不同考點出現的位置也就不一樣。推薦聽力TPO11 L1、TPO19 L3、TPO20 L4、TPO29 L1給各位TOEFLer課下練習，加深對托福聽力lecture結構特點的理解。