英语常用并列连词，如：and, but, so, yet, for, nor, or, not only:but also, either:or或neither:nor等连接两个或几个同等成分，这种结构称为并列结构。连接的同等成分可以是动词的宾语、介词短语或名词的定语等。
例1In general, the tests work most effectively when the qualities to be measured can be most precisely defined and least effectively when what is to be me
asured or predicted can not be well defined. (1995年真题)
分析：本句是由and连接的并列结构，每个并列结构中各有一个when引导的时间状语从句。在第二个时间状语从句中有一个what引导的主语从句。
译文：一般说来，当要测定的特征能得以十分精确的界定，测试的就最佳；反之，如果所要测定和预测的东西得不到明确的界定，那么测试的效果就最差。
例2Astrophysicists working with ground?based detectors at the South Pole and balloon?borne instruments are closing in on such structures, and may report their findings soon.(1998年真题)
分析：本句由and引导的并列结构，两个并列谓语分别是“are closing in on such structures”和“may report their findings soon”，它们的主语Astrophysicists后面有一个由分词短语充当的定语“working with ground?based detectors at the South Pole and balloon?borne instruments”。
译文：天体物理学家使用南极陆基探测器及球载仪器，正越来越近地观测这些云系，也许不久会报告他们的观测结果。
例3It is not that (不是)the scales in the one case, and the balance in the other, differ in the principles of their construction or manner ofworking; but that (而是) the latter (后者) is a much finer apparatus and of course much more accurate in its measurement than the former (前者)。(1993年真题)
分析：此句为not...but连接的并列复合句。在not和but后分别有一由that引导的表语从句。译文：这并不是说面包师或卖肉者所用的磅秤和化学家所有的天平在构造原理和工作方法上存在多少差别，而是说与前者相比，后者是一种更为精密的仪器，因而在计量上必然比前者准确得多。
例1In general, the tests work most effectively when the qualities to be measured can be most precisely defined and least effectively when what is to be me
asured or predicted can not be well defined. (1995年真题)
分析：本句是由and连接的并列结构，每个并列结构中各有一个when引导的时间状语从句。在第二个时间状语从句中有一个what引导的主语从句。
译文：一般说来，当要测定的特征能得以十分精确的界定，测试的就最佳；反之，如果所要测定和预测的东西得不到明确的界定，那么测试的效果就最差。
例2Astrophysicists working with ground?based detectors at the South Pole and balloon?borne instruments are closing in on such structures, and may report their findings soon.(1998年真题)
分析：本句由and引导的并列结构，两个并列谓语分别是“are closing in on such structures”和“may report their findings soon”，它们的主语Astrophysicists后面有一个由分词短语充当的定语“working with ground?based detectors at the South Pole and balloon?borne instruments”。
译文：天体物理学家使用南极陆基探测器及球载仪器，正越来越近地观测这些云系，也许不久会报告他们的观测结果。
例3It is not that (不是)the scales in the one case, and the balance in the other, differ in the principles of their construction or manner ofworking; but that (而是) the latter (后者) is a much finer apparatus and of course much more accurate in its measurement than the former (前者)。(1993年真题)
分析：此句为not...but连接的并列复合句。在not和but后分别有一由that引导的表语从句。译文：这并不是说面包师或卖肉者所用的磅秤和化学家所有的天平在构造原理和工作方法上存在多少差别，而是说与前者相比，后者是一种更为精密的仪器，因而在计量上必然比前者准确得多。
