上一講我們談到了文章的主題，這一講我們就開始研究文章的主題思想。首先明確一下概念，概括篇章（或段落）的思想就叫做主題思想。先看一下可能的問話形式：
II. CENTRAL IDEA
1. What is the main idea of the paragraph?
2. The main idea (central thought / idea of the paragraph is ______.
3. Which of the following sentences best expresses the main ides?
4. The main point of the paragraph is ______.
5. The paragraph centers on the point that ______.
6. Which of the following best states the theme of the paragraph?
主題思想在一篇文章中的表達可能有兩種方式---隱含式表達和直白式表達。隱含式表達是指在整個段落中沒有總括性的句子，全是陳述句或是情節句，主題思想是以一種隱含的方式表達出來的。直白式表達則恰恰相反，文章中有主題句。要注意的事，主題句的位置可能是在篇首，篇中或者是篇末，有時甚至有幾個主題句。請看一下這篇文章，辨別主題思想，并且區分式隱含式表達，還是直白式表達。
IIA.
During the American War of independence, women were involved in the active fighting in three ways. First, as members of a distinct branch of the Continental Army, referred to as "women of the Army," women staffed field hospitals and acted as military support in such roles as water carriers. In an emergency, women water carriers, who had plenty of opportunity to observe the firing of cannons, could replace a wounded comrade. The second way that women were involved in active fighting was as regular troop members who wore men's uniforms and fought side by side with their male counterparts. Theoretically, women were not supposed to be recruited into the Continental Army, but if a woman was a good soldier, no one made an issue of sex at a time when the army was so short of soldiers that boys not yet in their teens were also being recruited in violation of rules. Third, women were occasional fighters affiliated with local militia companies of committees of safety formed to protect the local community.
What is the main idea expressed in the passage?
A. Women played an important role in military hospitals during the Revolutionary war.
B. The Continental Army was successful in teaching women to fire cannons.
C. The services of women on committees of safety were crucial in winning the war.
D. Women were active in combat during the Revolutionary War.
這篇文章結構很清晰，第一句話是主體句，后面三句話從三個角度來進一步說明。所以，正確答案是D，又因為第一句話是總括性的句子，所以這是一種直白式表達。解答這類問題時，有以下四個技巧可以考慮：
1． 不為無關的細節說糾纏。
2． 仔細讀每一段的開頭，特別是最長的段落。
3． 如果文章只有一段，文章的開頭兩句極為重要。
4． 閱讀時，可以在你認為重要的句子，細節下畫線。
請再看一篇短文
IIB.
Joshua Bingham studied four years at the University of Paris and decided to leave before his graduation. He transferred to the University of Berlin and graduated with honors. Harvard Law School and, later, Boston College
provided him with an excellent legal background. He is presently a corporation lawyer in Miami, Florida.
這篇文章很顯然，所有的句子都是描述性的句子，所以就需要學生自己總結出主題思想來。綜合考慮后，我們可以寫出如下的主題思想：
Joshua Bingham received an excellent education。
下面這個練習供你們獨立完成，答案是 C。
IIC.
Pollution spoils our environment in many ways. The air we breathe, for instance, is constantly polluted by smoke and by chemicals such as carbon monoxide in the exhaust fumes of car and other kinds of motor vehicles.
For wild life, however, there are even greater dangers in the pollution of water - of rivers, for example, or lakes and seas. A good illustration of this is the oil released from tankers at sea. It kills all kinds of sea animals, including birds, whose feathers become covered with oil so they cannot fly, as well as fish and other forms of marine life, other causes of water pollution include power station, which release warm water into rivers. This kills the fish and plants which live there. These are only a few examples; there are many more.
What is the central idea of the passage?
A. It tells how many kinds of chemicals can be found in air and in the sea.
B. It tells how the air we breathe is polluted.
C. It tells in what ways the world becomes dirty and unsafe for living things.
D. It tells how rivers, lakes and seas are polluted.
