本段主题句为第二句，因为在however后面才是作者真正的看法，并在下文中进一步作了说明。
然而，我们也常常发现，有的主题思想并非直接由一、二个句子表述，而是在文中间接暗示着。这就需要读者根据文中细节进行概括与归纳，找出主题思想。例七：
It's no wonder that we have so many rejections for physical reasons in our Selective Service.Since October of 1948，some six million young men have been examined for military duty.Of these，more than a million were rejected as physically unfit for military service.To get two men today，the United States Army must call seven men.Of the five rejected three are turned down for physical reasons and two for mental problems.To get the 196thousand additional men we needed for Berlin，the government had to call up 750 thousand men.And the rejection rate is increasing each year.The reason for this problem is that we are underexercised as a nation.We look，instead of play.We ride，instead of walk.The way we live prevents us from being healthy.
本段中找不到某一句作为主题。根据文中的内容进行归纳，可找出主题思想，即：“The military's rejection rate for physical reason is increasing because this nation's lack of exercise is leading to poor health.”
在确定一篇文章的中心思想时，我们通常用快读的方法，从头至尾将全文浏览一遍，注意不要被个别词、句难住而停下来。要从上下文的连贯意思上来理解全文，看看全文谈论的是什么主题(Subject)、作者是从哪几个方面(Aspects)来进行阐述的、有关这个主题我们了解了些什么。这样，就可以比较有把握地概括出中心思想了。
第一段和第三段提到了victims(受害者)，第二段提到了入室行窃，但是第三段说明的共同问题是人们是否应拥有自卫武器来反对犯罪行为。因此只有选项C才能概括这三段所共同说明的问题，也就是此文的中心思想