例3
For years, nuclear-power advocates have claimed that nuclear power is the most economical form of energy available; but in light of a few facts, one begins to doubt this claim. The cost of building the Sequoiah nuclear plant, for example, exceeded a billion dollars. For this astronomical amount of money, one can expect this reactor to be out of operation approximately 30% of the time. After 30 or 40 years, it will become too “hot” to operate and will be shut down permenantly. Even though the reactor will be shut down, it will still be highly radioactive and will have to be totally encased（包住）in concrete and lead—all at a cost of another few million dollars—and guarded virtually forever. Nuclear power is neither cheap nor economical; it is both expensive and wasteful.
Q: Which of the following best summarizes the passage?
A) Nuclear power is the most inexpensive form of energy available.
B) Although nuclear power costs a lot, it can be used permanently.
C) It is not economical to use nuclear power.
D) Nuclear power is very popular in many countries.
本段共有六句。第一句提出的只是段落所要議論的主題，即核能的經濟效益問題，沒有明確地陳述作者對問題的看法。接下來四句以西克沃伊核電站為例，分析其造價高而工作壽命極其有限的弊病。最后一句合乎邏輯地引出作者分析這一事例而得出的結論。
由此可知，C）項，“使用核能經濟上不劃算”，為正確答案。A）、B）兩項與原文內容不符，D）項內容原文并未提及。
與主題句位于開段的情況相反，主題句位于收段時，段落的寫作程序是：表述細節(jié)的句子在前，概述性的句子居后，并以此收段。通常用歸納法撰寫的段落大抵如此。
位于收段的主題句往往陳述依據上文的細節(jié)推出的結論或建議、歸納的要點或共性，以及得出的觀察結果或印象。
例4
British and American universities are similar in their pursuit of knowledge as a goal but are quite different in their organization and operation. English universities and colleges are relatively small. American universities, which combine a number of different colleges and professional schools, are large, sometimes with 20,000 to 25,000 students on one campus. Teacher training colleges and polytechnics（工藝?？茖W校）are alternatives to the university course for some students in England, being established for specific purposes.
In contrast, virtually all schools of education, engineering and business studies, are integral （完整的）parts of universities in the United States. In England, universities receive about 70% of their financial support through Parliamentary （國會的） grants. Similarly, in the
United States, public institutions receive about 75% of their funds from local, state, and federal sources, but private colleges and universities receive little or no government support.
In England, personal finacial aid is provided by the government to over 80% of the students, through local education authorities, according to the parents’ income. In the U.S., student aid is given by the university or the sponsoring agency and is provided by private organizations and the state or federal governments. Obviously, British and American universities have similar educational aims but different means for achieving these aims.
Q: From the passage we learn that________.
A) the goal of education between British and American universities are quite different
B) the ways of running the universities are quite different between England and America
C) the British universities include a lot of colleges
D) the American universities include a lot of organizations
本文主要通過對照來說明英國大學與美國大學的不同點。第一句除指出它們都是以傳授知識作為目標這一共同點之外，主要概述它們的不同點，即在學校的組織和管理上有很大的區(qū)別。為說明這一看法（即段落的主題思想），作者隨即陳述若干細節(jié)，包括學校的規(guī)模、教學組織結構、辦學經費的來源以及學生助學金的來源與管理等四個方面。最后，作者使用邏輯承接詞obviously，既總結上述細節(jié)，又引出一個結論性的句子作為收段。顯然，首尾兩句表述的是同一個主題思想，只是句型結構和用詞略有不同。
從段落中可知，“英、美兩國大學的管理方法有所不同”，因而選B）。這句話實際上概括了段落大意。其余幾個選項均不合原意。
一般來說，一個段落只圍繞著一個主題來表述主旨大意，只是有些段落在結構上比較嚴謹，采用了前呼后應，兩次點題，從而更加突出主題思想的寫法。兩個主題句表述的是同一個主題，即后者重述前者所表述的思想內容。但兩個主題句在句型結構和用詞方面往往不盡一致，而且在內容上后者也不是前者的簡單重復，多半有所引申或順應其間細節(jié)的鋪敘而另有側重。
例5
The average population density of the world is 47 persons per square mile. Continental densities range from no permanent inhabitants in Antarctica to 211 per square mile in Europe.
In the western hemisphere, population densities range from about 4 per square mile in Canada to 675 per square mile in Puerto Rico. In Europe the range is from 4 per square mile in Iceland to 831 per square mile in the Netherlands. Within countries there are wide variations of population densities. For example, in Egypt, the average is 55 persons per square mile, but 1,300 persons inhabit each square mile in settled portions where the land is arable（可耕的）.
Q: The best title for the passage would be________.
A) Great Differences in Population Density of the World
B) The Average Population Density of the World.
C) Different Populations in Different Countries.
D) People and the World.
第一句“世界人口的平均密度為每平方英里47人”不是主題句，因為后續(xù)的句子都不是用來支撐它所表述的意思。該句僅起引介主題的作用，表明下文要論述的是 population density。據此可以確定本段論述的主要對象是人口密度，而且后續(xù)細節(jié)也都緊扣這一主題，如大陸的、西半球的、歐洲的以及一國之內的人口密度。再從所有細節(jié)涉及的共同點來看，都論及“人口密度的差距”這一方面。
據此，A）項，“世界人口密度的巨大區(qū)別”，為該文的標題。B）、C）兩項：“世界人口的平均密度”、“不同國家的不同人口”，都沒有準確點到題。至于D）項， “人民和國家”，則太籠統(tǒng)，也不切題。
沒有主題句的段落，如上一段，主要通過對細節(jié)的陳述含蓄地表現(xiàn)段落的主題思想。即使段落中有的句子表述的內容具有概括性，但不是演繹的前提，也不是歸納的結果，仍屬細節(jié)或僅起引介主題的作用。
對于無主題句的段落，不可能采用辯認主題句的方法來獲取段落的主題思想。這里，宜采用醞釀段落題要或標題的方法，把不同的細節(jié)所集中論述的要點概括出來。
盡管不一定達到主題句那樣完整，但只要切合段落的主題，即可表達該段的主題思想。
使用這種方法，要求讀者在正確理解所有細節(jié)的基礎上，發(fā)揮自己的邏輯概括能力。
3.1.2 辯認主題展開的重要細節(jié)(Recognizing Primary Supporting Details)
細節(jié)是組成文章的主體部分，是用來闡明主旨大意的，或者說，是用來支撐主題思想的。要注意識別句子的功能及文中的承接語，以便充分理解文章的主旨及具體細節(jié)和事實
For years, nuclear-power advocates have claimed that nuclear power is the most economical form of energy available; but in light of a few facts, one begins to doubt this claim. The cost of building the Sequoiah nuclear plant, for example, exceeded a billion dollars. For this astronomical amount of money, one can expect this reactor to be out of operation approximately 30% of the time. After 30 or 40 years, it will become too “hot” to operate and will be shut down permenantly. Even though the reactor will be shut down, it will still be highly radioactive and will have to be totally encased（包住）in concrete and lead—all at a cost of another few million dollars—and guarded virtually forever. Nuclear power is neither cheap nor economical; it is both expensive and wasteful.
Q: Which of the following best summarizes the passage?
A) Nuclear power is the most inexpensive form of energy available.
B) Although nuclear power costs a lot, it can be used permanently.
C) It is not economical to use nuclear power.
D) Nuclear power is very popular in many countries.
本段共有六句。第一句提出的只是段落所要議論的主題，即核能的經濟效益問題，沒有明確地陳述作者對問題的看法。接下來四句以西克沃伊核電站為例，分析其造價高而工作壽命極其有限的弊病。最后一句合乎邏輯地引出作者分析這一事例而得出的結論。
由此可知，C）項，“使用核能經濟上不劃算”，為正確答案。A）、B）兩項與原文內容不符，D）項內容原文并未提及。
與主題句位于開段的情況相反，主題句位于收段時，段落的寫作程序是：表述細節(jié)的句子在前，概述性的句子居后，并以此收段。通常用歸納法撰寫的段落大抵如此。
位于收段的主題句往往陳述依據上文的細節(jié)推出的結論或建議、歸納的要點或共性，以及得出的觀察結果或印象。
例4
British and American universities are similar in their pursuit of knowledge as a goal but are quite different in their organization and operation. English universities and colleges are relatively small. American universities, which combine a number of different colleges and professional schools, are large, sometimes with 20,000 to 25,000 students on one campus. Teacher training colleges and polytechnics（工藝?？茖W校）are alternatives to the university course for some students in England, being established for specific purposes.
In contrast, virtually all schools of education, engineering and business studies, are integral （完整的）parts of universities in the United States. In England, universities receive about 70% of their financial support through Parliamentary （國會的） grants. Similarly, in the
United States, public institutions receive about 75% of their funds from local, state, and federal sources, but private colleges and universities receive little or no government support.
In England, personal finacial aid is provided by the government to over 80% of the students, through local education authorities, according to the parents’ income. In the U.S., student aid is given by the university or the sponsoring agency and is provided by private organizations and the state or federal governments. Obviously, British and American universities have similar educational aims but different means for achieving these aims.
Q: From the passage we learn that________.
A) the goal of education between British and American universities are quite different
B) the ways of running the universities are quite different between England and America
C) the British universities include a lot of colleges
D) the American universities include a lot of organizations
本文主要通過對照來說明英國大學與美國大學的不同點。第一句除指出它們都是以傳授知識作為目標這一共同點之外，主要概述它們的不同點，即在學校的組織和管理上有很大的區(qū)別。為說明這一看法（即段落的主題思想），作者隨即陳述若干細節(jié)，包括學校的規(guī)模、教學組織結構、辦學經費的來源以及學生助學金的來源與管理等四個方面。最后，作者使用邏輯承接詞obviously，既總結上述細節(jié)，又引出一個結論性的句子作為收段。顯然，首尾兩句表述的是同一個主題思想，只是句型結構和用詞略有不同。
從段落中可知，“英、美兩國大學的管理方法有所不同”，因而選B）。這句話實際上概括了段落大意。其余幾個選項均不合原意。
一般來說，一個段落只圍繞著一個主題來表述主旨大意，只是有些段落在結構上比較嚴謹，采用了前呼后應，兩次點題，從而更加突出主題思想的寫法。兩個主題句表述的是同一個主題，即后者重述前者所表述的思想內容。但兩個主題句在句型結構和用詞方面往往不盡一致，而且在內容上后者也不是前者的簡單重復，多半有所引申或順應其間細節(jié)的鋪敘而另有側重。
例5
The average population density of the world is 47 persons per square mile. Continental densities range from no permanent inhabitants in Antarctica to 211 per square mile in Europe.
In the western hemisphere, population densities range from about 4 per square mile in Canada to 675 per square mile in Puerto Rico. In Europe the range is from 4 per square mile in Iceland to 831 per square mile in the Netherlands. Within countries there are wide variations of population densities. For example, in Egypt, the average is 55 persons per square mile, but 1,300 persons inhabit each square mile in settled portions where the land is arable（可耕的）.
Q: The best title for the passage would be________.
A) Great Differences in Population Density of the World
B) The Average Population Density of the World.
C) Different Populations in Different Countries.
D) People and the World.
第一句“世界人口的平均密度為每平方英里47人”不是主題句，因為后續(xù)的句子都不是用來支撐它所表述的意思。該句僅起引介主題的作用，表明下文要論述的是 population density。據此可以確定本段論述的主要對象是人口密度，而且后續(xù)細節(jié)也都緊扣這一主題，如大陸的、西半球的、歐洲的以及一國之內的人口密度。再從所有細節(jié)涉及的共同點來看，都論及“人口密度的差距”這一方面。
據此，A）項，“世界人口密度的巨大區(qū)別”，為該文的標題。B）、C）兩項：“世界人口的平均密度”、“不同國家的不同人口”，都沒有準確點到題。至于D）項， “人民和國家”，則太籠統(tǒng)，也不切題。
沒有主題句的段落，如上一段，主要通過對細節(jié)的陳述含蓄地表現(xiàn)段落的主題思想。即使段落中有的句子表述的內容具有概括性，但不是演繹的前提，也不是歸納的結果，仍屬細節(jié)或僅起引介主題的作用。
對于無主題句的段落，不可能采用辯認主題句的方法來獲取段落的主題思想。這里，宜采用醞釀段落題要或標題的方法，把不同的細節(jié)所集中論述的要點概括出來。
盡管不一定達到主題句那樣完整，但只要切合段落的主題，即可表達該段的主題思想。
使用這種方法，要求讀者在正確理解所有細節(jié)的基礎上，發(fā)揮自己的邏輯概括能力。
3.1.2 辯認主題展開的重要細節(jié)(Recognizing Primary Supporting Details)
細節(jié)是組成文章的主體部分，是用來闡明主旨大意的，或者說，是用來支撐主題思想的。要注意識別句子的功能及文中的承接語，以便充分理解文章的主旨及具體細節(jié)和事實