一段文章的中心思想常常由主題句(Topic Sentence)表達。主題句常常位於段首或段尾處，間或出現在段落中間。同樣，一篇文章的中心思想也常常在開始或結尾段點出。因此在閱讀中，我們要特別注意文章的.開頭或結尾。例四：
English is clearly an international is spoken by pilots and airport control operators on all the airways of the 70 percent of the worlds radio programs are in English.
本段主題句為首句，其後的內容句均說明首句。例五：
Some students prefer a strict teacher who tells them exactly what to rs prefer to be left to work on their l others like a democratic discussion type of one teaching method can be devised to satisfy all students at the same time.
本段中心思想在結尾句得到體現，它是此段內容的結論。例六：
For adults a cold is not that ver，this is not the case for symptoms in children may be signs of more serious diseases and should be given prompt medical attention.
本段主題句為第二句，因為在however後面才是作者真正的看法，並在下文中進一步作了說明。
然而，我們也常常發現，有的主題思想並非直接由一、二個句子表述，而是在文中間接暗示著。這就需要讀者根據文中細節進行概括與歸納，找出主題思想。