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1　主题句的段落实例M ost of the time bone tumors are treated w ithradiation.Most tumors are pretty sensitive and radiationdoses can be given that don’thurt the bone but reliablykill the tumor cells. Radiation very quickly takes awaythe pain and allows the bone to repair itself and becomestrong again.主题句后面的句子说明肿瘤为什么能适应放射治疗以及治疗的作用和效果,因而对主题句作了进一步深入和具体化的描述。Statins, which include drugs such as Zocor,Pravachol and Lipitor, have had a remarkable im-pact on heart disease.These drugs rid the bloodstreamofcholestero,l a fatty substance produced primarilyby theliver and acquired from dietary sources. Statins are par-ticularly good at removing low-density lipoprotein (LDL)cholestero,l considered the“bad”cholestero,l which canbuild up in the blood vessels to cause blockages in arter-ies that supply the heart and brain thus preventing heartdisease and stroke.

随后两个句子的主语these drugs和statins都是围绕主题句的中心思想展开,具体说明他汀类药物(statins)如何能预防心脏病的具体过程和机制。

One of the most compelling arguments againstthe association between brain tumors and cell phoneuse is based on the location of the tumor.Mostpeopletend to place the cellphone on the same side of the headwhen they speak. Since the RF energy falls off veryquickly with increasing distance from the antenna, thedose ofenergy on the side of the brainwhere the phone isheld ismuch larger than on the other side of the brain.Several studies in cellphone userswith brain tumorshavedemonstrated that there is no significant correlation be-tween the location of the tumor and the side ofpreferenceof the cell phone user. Likewise, tumors in cell phoneusers are not significantly more frequent in areas of thebrain closest to the ear than in other areas of the brain.One study, which did find a tendency formore tumors toappear on the side where the cell phone was used,showed that these tumorswere not located in the part ofthe brain closest to the antenna. The result thereforemostlikely represented an accidental association.

主题句提出脑瘤与手机使用之间位置关系的争议问题。后面的句子就此展开说明,对患有脑瘤的手机使用者好几起研究表明脑瘤发生的位置与手机使用在面部哪一侧没有明显联系,同样,脑瘤发生的部位也不总是靠近耳朵的地方。有一项研究,尽管脑瘤发生的部位偏向于手机使用的同一侧,但肿瘤的部位并非离手机天线最近,因而被视为是偶然联系(即个别现象)。主题句除多数位于段落开头外,有时也会出现在段落末尾,起概括全段的作用。下面就是一个典型的例子。

After having a baby, many women have moodswings. One minute they feel happy, the next minutethey start to cry. Theymay feel a little depressed, have ahard time concentrating, lose their appetite or find thatthey can’t sleep well even when the baby is asleep.These symptoms usually start about3 to 4 days after de-livery andmay last several days. Ifyou’re a newmotherand have any of these symptoms, you have what arecalled the“baby blues.”“The blues”are considered anormalpartofearlymotherhood and usually go awaywith-in 10 days after delivery. However, some women haveworse symptoms or symptoms last longer.This is called“postpartum depression.”

本段首先叙述产妇分娩后情绪波动、精神压抑、注意力不集中、食欲不佳、睡眠不良等表现,通常仅持续数日,是新妈妈的“产后情绪不稳定”(baby blues)。有些产妇症状更重,时间更长,则称为“产后抑郁症”。最后一句归纳了全段内容,体现了本段的主题。论述性的文体常采用主题句的写作技巧,但也不是所有的段落都有主题句,特别是报道体的文章,则很少使用主题句。另外,有时主题句不是明确表达出来,而是暗含在段落之中,阅读这样的文章,就需要自己根据文章的细节来分析,概括出段落的主题思想。

2　以定义为首句的段落实例Foot-and-mouth diseaseis a highly infectious viraldisease of animals that spreadswidely and quickly. It af-fects cows, pigs, sheep and deer. Affected an本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。