一、知段落的构成——抓主题句
(一)段落的构成
英语文章段落结构一般由三部分构成：主题句(topic sentence), 扩展句(development sentence)和结论句(closing sentence/concluding sentence)。主题句点出段落的主题，扩展句解释说明或论证主题，结论句总结、归纳或概括主题。
1．主题句
主题句，就是段落的核心句、纲领句、主旨句、中心思想句，言简意赅，主旨鲜明。它是段落的灵魂，表达段落的主题，在英语文章段落中居于主导地位，其他句子都要围绕它而展开。英语文章一般喜欢开宗明义，所以主题句一般位于文章段首，但有时也在段中或段尾。
2．扩展句
扩展句就是为主题句起解释说明或论证作用的句子。扩展句一般长度适中，有一定的条理和逻辑。扩展句的展开方法多种多样，通常采用的方法有举例说明、描述、定义、比较对照、因果分析、分类等。
3．结论句
结论句就是总结句，会重述或总结段落的中心论点，与主题句相呼应。需要指出的是，英文段落中结论句并不多见，我们通常看到英语的文章段落结构60%～70%都是由“主题句＋扩展句”构成。
[例] Why fiction is superior to textbooks lies in their imagination (主题句：以自问自答的方式提出段落主题). Authors of the fictions always create attractive characters so as to give his opinion about nature and the society as well as life (扩展句1). It not only provides knowledge, but also teaches us what is the right attitude toward life (扩展句2). For instance, we can learn from Gone with the Wind how to be a strongwilled person; from Jack London, how to love life (扩展句3：基于上述观点，进一步举例说明). We can be stimulated to overcome all obstacles to realize our ambitions (扩展句4). So, fictions enable people to form their positive view of life, the spirit of optimism and invincible courage, and provide us with an opportunity to learn and to practice, while textbooks barely can (结论句：归纳总结段落主题)．
