托福听力的最大特点，就是在每段听力结束之后，题目上出现在屏幕上。因此，很多人觉得听托福听力时非常茫然，甚至有时听完后仍然没办法做对题目。同时，也有不少人觉得，听完一段托福听力后，虽然大意全都听懂了，然而落实到题目上，还是会出现不少错误。这其中的原因，无非是不知道托福听力中会考察哪些重点。也就是说，如果我们把托福听力考试比喻成一个案件的话，那么如果我们在完全摸不清线索的情况下，确实会不知道从何下手。因此，为了更好地解开托福听力的谜团，我们需要掌握必要的线索。

线索一、开头前几句

托福听力的开头前几句，是极为重要的线索。每段听力之后的第一题，都是与主旨相关的题目。而听力内容的主旨，大部分都可以从开头的前几句中抓到。我们来看一个例子：

以下是托福听力中对话开头的第一句：

Student: Hi, professor Handerson. That was a really interesting lecture in class today.

仔细分析这句话后，我们至少可以得到两个重要的信息：第一，这段对话发生在刚刚上完一节课之后；第二，学生应该是对之前课上的某个要点存有疑问才来找教授的（托福对话一般是按照“提出问题—分析问题—解决问题”这一模式进行）。

接着，我们来看一下这段对话对应的第一道题目：

Question: Why does the man go to see the professor?

A. To ask for heap in choosing a topic for his term paper

B. To ask the professor to explain how to complete an assignment

C. To ask about a point raised in a recent lecture

D. To offer to help the professor with her research project

根据第一句话中暗含的两个信息，我们可以认定答案为C。因为C选项中的“recent lecture”符合第一句话中暗含的第一个信息，“ask about a point”符合第二个隐含信息。

我们再来看一段对话中的第一句话：

Student: Hi, I... I am sorry to interrupt, could I ask you a few questions?

这句话看上去作用不大，但却与题目与着很密切的关系：

Question: What is the conversation mainly about?

A. Changes that will be made in food choices offered to students

B. Food-safety procedures followed by the cafeteria staff

C. Issues related to the cafeteria's food policy

D. Common complaints about the food served in the cafeteria

学生说的第一句话中，有一个关键词“question”，可见学生的目的并不是要讨论“change”“procedure”或“complaint”。因此，答案可以初步锁定为选项C。同时，选项C中有关键词“issue”，意思为“问题”，与学生说的“question”类似。当然，这些只是猜测，我们需要再听一些对话的开头部分，才能真正确定C选项为正确答案。

同时，开头前几句对讲座来说同样十分重要，因为通过前几句，我们也很有可能得知一个讲座的主题。我们来看一个例子，以下是一个讲座的开头：

Professor: OK, today we are going to continue our discussion of plant life in coastal salt marshes of North America. Salt marshes are among the least inviting environments for plants.  The water is salty, there is little shade and the ocean tide comes in and out, constantly flooding the marsh, so the variety of plants found in salt marshes is limited, but there is a plant genus that thrives there, the Spartina. In fact, the Spartina genus is the dominant plant found in salt marshes. You can find one type of  the Spartina, Saltmarsh Cordgrass, growing in low marsh areas. In higher marsh areas, you are likely to find a Spartina commonly called Salt-meadow Hay. So how is the Spartina able to survive in an environment that would kill most plants? Well, it is because salt marsh grasses have found ways to adapt to the conditions there.

以下是与之对应的题目：

Question: What is the lecture mainly about?

A. The effect of the tidal flow on the salt marsh

B. Ways that some plants have adapted to living in salt marshes

C. The process of osmoses in plants

D. Differences between plants that grow in salt marshes and plants that grow elsewhere

根据以上讲座开头中的最后两句话，我们可以知道选项B为正确答案。

我们再来看一个例子：

Professor: All right, let’s continue our discussion of portrait artists(portraitist) and portraiture. Who remembers any of the important points we made last time? Sandra?

Student: Well, artists have done portraits of people for centuries, of famous people and regular people, and most portraits convey the artists’ personal vision, like their feelings and insights about a person.

Professor: Great, that’s a crucial point, and I’d like to explore that a little today. A great example of that, that vision in portraiture, is Cecilia Beaux. Cecilia Beaux was born in 1854, and after learning to paint and studying with several important artists of the time, Beaux became known as one of the best portrait painters in the United States. She was very successful. She even had portraits of the wife and children of Theodore Roosevelt, while he was president. Some did not get much more prestige than that. Now, those portraits also reflect the kind of subjects that Beaux tended to use, which were mostly women and children. For example, in her first major work, her subjects were ..., the painting featured her sister and her nephew. Yes, Mark?

以下为对应的题目：

Question: What is the purpose of the discussion?

A. To compare the portrayal of different subjects in Cecllia Beaux`s portraits

B. To examine the influence of women artists in the nineteenth century

C. To explain how The Dreamer differs from Impressionist art

D. To demonstrate how Cecilia Beaux's point of view is reflected in her art

通过教授与学生的互动，我们可以知道，教授在这次讲座中想要讨论某个画家的观点是如何反映在画作当中的。因此，答案选D。

这里必须指出，虽然对话和讲座的开头前几句很重要，但并不是所有的主旨，都能够从开头的前几句中抓到。

在一些对话中，有时候主旨恰恰出现在结尾处。我们来看一个例子：

Bob: Still, I wish we could read whole novels by Joyce and discussed them in class.

Professor: That's what happens in my Master Writer Class.

Bob: Master Writer Class?

Professor: Yeah, I teach one on Joyce every spring. It's such a privilege, spending an entire term diving into a single body of work. And my students, they bring so much insight to the table that it's easy to forget who the professor is.

Bob: Oh, wow. That could actually solve my dilemma, uh, what I originally wanted to ask you ? um, I am working on my schedule for next term, and I've got room for one more course, and I'd like to take more literature. Could I take your Master Writer Class on Joyce?

Professor: I'm sorry. I should have mentioned. Uh, Master Writer is an advanced seminar. So students need to get a strong foundation in literary theory and criticism before I let them in the room.

以下为对应的题目：

Question: Why does the man go to see the professor?

A. To discuss a grade he received on a paper

B. To get advice about which course he should take next term

C. To ask a question about a reading assignment

D. To request permission to take an advanced course

这个片段出现在整个对话的后半部分中。听到这里，我们才能判断出学生来找教授的目的是询问下学期应该上什么课。因此，答案选B。

我们再来看一个例子：

Student: Wow, really? Well, I am looking for a topic for my term paper, so maybe I could do it on these glowing jellyfish. That’s why I wanted to ask you about them, you know, to find out if there was really something to write about.

与之对应的题目为：

Question: Why does the student go to see the professor?

A. To obtain notes from a class she missed

B. To discuss a conference she attended

C. To ask about a possible topic for a research paper

D. To clarify information about volunteering in the community

同样地，学生的这句话仍然出现在对话末尾。由此，我们可以知道正确答案为选项C。

在一些对话之后，也出现过多选类型的主旨题，即要求选出两个或三个对话中涉及到的主旨。这时候，我们也没办法仅凭对话的前几句，就抓到全部的主旨。我们来看一个例子：

片断1

Girl: Did you register already for your classes next semester?

Boy: Yes, I did.

Girl: What are you taking?

Boy: Um…contemporary literature, English style, um… the teaching seminar, and I still have to do my student teaching. I’m gonna help teach a writing class of the junior high.

Girl: That’s a heavy schedule.

片断2

Boy: So you are not writing any poetry, I imagine.

Girl: No, I was actually thinking about revising some of my poems and sending them into places for publication.

Boy: Cool, you should. Um, did you hear about that new poetry club, The Poetry Kitchen?

Girl: Yeah, no time.

Boy: It’s fun. It’s Sunday night. You don’t do anything at Sunday nights?

Girl: I do homework Sunday nights.

以下为与之对应的题目：

Question: What are the students mainly discussing? Click on 2 answers

A.Their courses for next semester

B.Their plans for the weekend

C.A poetry club

D.A class assignment

我们只有在听完片断1和片断2之后，才能得出以上题目的答案，即选项A和选项C。

在讲座中，我们有时也需要听完全部，才能判断出主旨是什么。我们来看一个例子：

Professor: All right, so far we have been looking at some of the core areas of linguistics, like syntax, phonology, semantics, and these are things that we can study by looking at one  language at a time, how sounds, and words, and sentences work in a given language. But the branch of historical linguistics, involves the comparison of several different languages, or the comparison of different stages of a single language. Now, if you are comparing different languages, and you notice that they have a lot in common. Maybe they have similar sounds and words that correspond to one another that have the same meaning and that sound similar.

与之对应的题目是：

Question: What does the professor mainly discuss

A. Same characteristics that are common in several languages

B. A way to represent languages that are genetically related.

C. Which languages probably evolved from Proto-Indo-European

D. Linguists' opinions about why languages change over time

这道题选B，然而它并不能仅仅通过教授的开场判断出来。有时候，教授开头的几句话很可能只是一个过度和引导，真正的主旨可能在很后面才出来。

我们再来看一个例子：

Professor: So how many of you have seen the Milky Way, the Milky Galaxy in the sky? You, you have?

Student: Yeah, I was camping, and there was no moon that night, it was super dark.

Professor: Anybody else? Not too many. Isn’t that strange that the Milky Way is the galaxy that the planet earth is in, and most of us have never seen it? Now, what’s the problem here?

Student: Light pollution, right? From street lights and stuff ...

Professor: Yes, Especially unshielded street light, you know, ones that aren’t pointed downward. Now, here’s an irony, the building we are in now, the astronomy building not far from our observatory, has unshielded lights.

以下是与之对应的题目：

Question: What is the lecture mainly about?

A. Recent advances in technology used by astronomers

B. How radio astronomy has led to advances in communication technology

C. Important discoveries made by radio astronomers

D. Difficulties astronomers have in observing the universe

我们可以看到，教授一开始是用提问的方式开场。通过教授与学生的对话，讲座的主题似乎是光污染。但是，这道题目的正确答案为D。

可见，在一些情况下，我们还是需要耐心听完对话和讲座，才能判断出其中的主旨。