二，抛砖引玉。顾名思义，这种文章开头绝不会是文章中心。这类文章一般会在开头引入一个例子（这种例子的典型的特点是有具体时间人物事件）。然后，在通常情况下，对该例子进行转折，或者负评价（本质上也是转折，与转折分开论述是因两者表现形式不一样），或者是总结。

（一）转折的基本标志诸如：however, yet, but的出现一般标志着文章主题的出现。不过，还有一些转折大家庭里的词汇也是大家需要留意的，如：despite, still, in fact.或者一些意义上表示转折的词如：surprisingly（如99年6月PR那篇文章），today（如2000年12月垃圾回收那篇文章）等等。这些转折一般出现在第一段末尾或者第二段开头。转折在抛砖引玉型文章中最常出现。

（二）其次是负评价，虽然没有转折词，但是对前文进行的否定型的评价一样意味着文章中心的出现。最典型的一篇文章要算93年6月关于时尚这篇文章的论述了，第一段说了一大堆，第二段开头：Changing fashions are nothing more than the intentional creation of waste 马上对时尚做了一个负评价。对整个文章的褒贬定了一个调。把这句话读懂，大意就可以有个了解了。在做题时甚至是细节题都可以直接排除一些正评价的选项了。

（三）开头引一段例子，其后进行总结的文章诸如99年一月英国草盖屋一文第一段尾出现总结性评价。这类文章中心出现是以therefore, as a result, so, thus, hence等词汇的出现为标志的。在此不一一赘述 。在做抛砖引玉型文章时也需注意以下一个特点或者叫做难点，即有些文章转折出现得靠后，这就要求同学们把文章重心的理解放在靠后出现的转折后面的内容。这种文章有以下几篇：97年6月份关于洛杉矶大地震（despite出现在第四段首），95年一月英国工作一文（but出现在第三段首），99年6月玩具一文（第三段首出现转折），02年1月道德下降一文（第三段首出现转折）02年6月心理压力一文（第三段首出现转折）。以97年6月份关于洛杉矶大地震这篇文章为例我们稍作分析。

After the violent earthquake that shook Los Angeles in 1994, earthquake scientists had good news to report: The damage and death toll（死亡人数）could have been much worse.

More than 60 people died in this earthquake. By comparison, as earthquake of similar intensity that shook America in 1988 claimed 25,000 victims.

Injuries and deaths were relatively less in Los Angeles because the quake occurred at 4:31 a.m. on a holiday, when traffic was light on the city's highways. In addition, changes made to the construction codes in Los Angeles during the last 20 years have strengthened the city's buildings and highways, making them more resistant to quakes.

Despite the good new, civil engineers aren't resting on their successes. Pinned to their drawing boards are blueprints（蓝图）for improved quake-resistant buildings. The new designs should offer even greater security to cities where earthquakes often take place.

In the past, making structures quake-resistant meant firm yet flexible materials, such as steel and wood, that bend without breaking. Later, people tried to lift a building off its foundation, and insert rubber and steel between the building and its foundation to reduce the impact of ground vibrations. The most recent designs give buildings brains as well as concrete and steel supports. Called smart buildings, the structures respond like living organisms to an earthquake's vibrations. When the ground shakes and the building tips forward, the computer would force the building to shift in the opposite direction.

The new smart structures could be very expensive to build. However, they would save many lives and would be less likely to be damaged during earthquakes.

前三段全部在谈地震的影响及死亡人数少的原因，不知道文章中心在哪儿，第四段开头出现：Despite the good new, civil engineers aren't resting on their successes.紧跟着出现文章主题：Pinned to their drawing boards are blueprints（蓝图）for improved quake-resistant buildings.所以在做主题题时关键在与把这一句读出来。这样在做最后一题

25. The author's main purpose in writing the passage is to ________.

A) compare the consequences of the earthquakes that occurred in the U.S.

B) encourage civil engineers to make more extensive use of computers

C) outline the history of the development of quake-resistant building materials

D) report new developments in constructing quake-resistant buildings

的时候就不会出错了。