尽管主旨题已经不再是四级阅读的必考题型，但能够准确的把握文章的主题对解决其他各种题型还是大有裨益的。尤其是近年来大量增加的观点题和推理概括题，其答案的设计跟文章的主题有着密切的关系。

主题就是一篇文章的根本，就测试学来看，依据一篇文章来出的题目都是围绕着主题进行设计，所以把握住了文章的主题就找到了破解各题的大方向。如何才能快速准确地找到文章的主题呢？

要想找到文章的主题，必须先了解四级文章的结构特点。四级的文章按结构可以分成两大类：总分结构和观点分述结构。从考试操作层面来看，最简单的方法就是根据段落的数量来划分——五段以内的（包括五段）基本都是总分结构;大于五段的基本可按观点分述结构来处理。

如何把握总分结构文章的主题？总分结构文章的布局如下：总述（提出观点）→分述（论述观点）→总述（强调观点）。总分结构文章的主题一般都在文章的首段。如果首段出现转折词，主题往往是首段转折句;如果首段没有明显的转折，则主题往往是首段首句。如果首段无转折，且只是描述某种现象，则需要关注文章的二段或三段，这时候文章的主题很可能是二段或三段段首的转折句。例如：

Why does cream go bad faster than butter？ Some researchers think they have the answer， and it comes down to the structure of the food， not its chemical composition—a finding that could help rid some processed foods of chemical preservatives.

Cream and butter contain pretty much the same substances， so why cream should sour much faster has been a mystery. Both are emulsions—tiny globules （小球体） of one liquid evenly distributed throughout another. The difference lies in what’s in the globules and what’s in the surrounding liquid， says Brocklehurst， who led the investigation.

In cream， fatty globules drift about in a sea of water. In butter， globules of a watery solution are locked away in a sea of fat. The bacteria which make the food go bad prefer to live in the watery regions of the mixture. “This means that in cream， the bacteria are free to grow throughout the mixture，” he says.

When the situation is reversed， the bacteria are locked away in compartments （隔仓室） buried deep in the sea of fat. Trapped in this way， individual colonies cannot spread and rapidly run out of nutrients （养料）。 They also slowly poison themselves with their waste products. “In butter， you get a self-limiting system which stops the bacteria growing，” says Brocklehurst.

The researchers are already working with food companies keen to see if their products can be made resistant to bacterial attack through alterations to the food’s structure. Brocklehurst believes it will be possible to make the emulsions used in salad cream， for instance， more like that in butter. The key will be to do this while keeping the salad cream liquid and not turning it into a solid lump.

这篇文章一共五段，可以按总分结构来提取主题，其首段无转折词，但段首句是问句，一般来说如果段首出现问句，后面的内容就是在对其作答。所以这篇文章的主题就是在解释cream比butter坏得快的原因就是他们的内部结构不同。这篇文章没有专门考主旨题，但考了一个观点题

According to Brocklehurst， we can keep cream fresh by ________.

A） removing its fat

B） killing the bacteria

C） reducing its water content

D） altering its structure（D）

结合文章的主题我们不难猜出答案应该跟食物的结构有关，所以应该选D项。

如何把握观点分述结构文章的主题？观点分述结构的文章包括以下几个部分：现象1（观点1）→理由（解释现象1或观点1）→反对理由→结论（现象2或观点2）。对于观点分述型文章，找主题有两种方法：一种是首段观点+末段观点（如果后面段落的段首出现转折词，则否定首段观点，肯定末段观点）;另一种方法是直接看后半部分段落开头的转折句。例如：

Believe it or not， optical illusion （错觉） can cut highway crashes.

Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. Bent stripes， called chevrons （人字形）， painted on the roads make drivers think that they are driving faster than they really are， and thus drivers slow down.

Now the American Automobile Association Foundation for Traffic Safety in Washington D.C. is planning to repeat Japan’s success. Starting next year， the foundation will paint chevrons and other patterns of stripes on selected roads around the country to test how well the patterns reduce highway crashes.

Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents， according to the foundation. To help reduce those accidents， the foundation will conduct its tests in areas where speed-related hazards are the greatest—curves， exit slopes， traffic circles， and bridges.

Some studies suggest that straight， horizontal bars painted across roads can initially cut the average speed of drivers in half. However， traffic often returns to full speed within months as drivers become used to seeing the painted bars.

Chevrons， scientists say， not only give drivers the impression that they are driving faster than they really are but also make a lane appear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.

这篇文章一共6段，应该按观点分述型文章来找主题。即首段观点+末段观点。所以该片文章的主题是optical illusion （错觉） can cut highway crashes，而这种optical illusion （错觉）来自一种新的路面设计Chevrons，这种设计可以让驾驶员自动减速从而减少高速公路上的交通事故。这篇文章考到了主旨题：

The passage mainly discusses ________.

A） a new way of highway speed control

B） a new pattern for painting highways

C） a new approach to training drivers

D） a new type of optical illusion

根据文章主题，答案应该是选A。