一、平行结构的基本原则

　　在许多英语句式中，平行结构是延长英文句子的重要因素之一。像简单的并列连词and, or, but等就有这种类型的含义，它们要求在结构和功能上保持一致。因此运用平行结构的基本原则就是以同类语法形式来表达同类概念，用来表达强调与其、节约用词的修辞效果。真题上的例子有许多：For the time, attention, and money of the art-loving public, classical instrumentalists must compete not only with opera houses, dance troupes, theater companies, and museums, but also with the recorded performances of the great classical musicians of the 20th century. (2011-T1)该句就是由not only……but also连接两个with短语，构成的平行结构。再来一句Now the company is suddenly claiming that the 2002 agreement is invalid because of the 2006 legislation, and that only the federal government has regulatory power over nuclear issues. 该句中也存在两个that引导的宾语从句。如今，Entergy公司突然发出声明：根据2006年的法规，2002年的协议无效，而且只有联邦政府对核问题具有监管权。

　　二、构成并列结构的连接词

　　最熟悉的莫过于and了，但是不仅仅只有and, 表示同等关系中的besides副词连接词也是常见。它们所连接的前后句在语法地位上平等一致。这样的词还有and, not only…but also, neither…nor, moreover, furthermore, in addition, what’s more.在2005年阅读第四篇中就有这样一个例子：Americans no longer expect public figures, whether in speech or in writing, to command the English language with skill and gift. Nor do they aspire to such command themselves.这句中是由否定词nor连接的并列句，并且第二个分句还是由nor引导，发生了倒装结构。另外，由either…or…, otherwise, or else,等表示选择的连接副词连接的句子，表达的是一种选择关系。

　　还有就是表示转折的并列连词，如but, yet, however, while, whereas,not…but等。真题例句：The process is not the road itself, but rather the attitudes and feelings people have, their caution or courage, as they encounter new experiences and unexpected obstacles. 这里就是一个由not…but连接的表示转折关系的并列句。

　　最后一种熟悉的并列结构就是因果并列句。这种句子通常由so, therefore为代表。Often it’s the delivery which causes the audience to smile, so speak slowly and remember that a raised eyebrow or an unbelieving look may help to show that you are making a light-hearted remark.该句中就是由so连接的两个并列句。

　　另外需要注意一点就是很多副词也有连接的含义，但是它们并不能连接句子，只能由分号或者and连接。例如：She felt very tired; therefore she went to bed early.

　　三、平行并列结构中的一致性问题

　　在平行结构中，为了使句子前后保持平衡，句中的并列成分应该在结构上保持一致性。The instrument has been welcomed by user because of its stability in serviceability, reliability in operation and simplicity in maintenance.这句中its stability in serviceability, reliability in operation and simplicity in maintenance这三者存在由and连接的并列关系，并且在结构上保持了一致。翻译的时候也要注意其翻译的一致性：该仪器性能稳定，操作可靠，维修方便，因而受到用户欢迎。

　　最后补充说明一定，并列结构在完形中出现的频率很高，而且做题的技巧往往就集中在这些并列中。比如，如果在not only后挖空的话，答案往往就与but also之后的词有关。