英語常用并列連詞，如：and, but, so, yet, for, nor, or, not only:but also, either:or或neither:nor等連接兩個或幾個同等成分，這種結構稱為并列結構。連接的同等成分可以是動詞的賓語、介詞短語或名詞的定語等。

　　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年真題)

　　分析：本句是由and連接的并列結構，每個并列結構中各有一個when引導的時間狀語從句。在第二個時間狀語從句中有一個what引導的主語從句。

　　譯文：一般說來，當要測定的特征能得以十分精確的界定，測試的就最佳；反之，如果所要測定和預測的東西得不到明確的界定，那么測試的效果就最差。

　　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年真題)

　　分析：本句由and引導的并列結構，兩個并列謂語分別是“are closing in on such structures”和“may report their findings soon”，它們的主語Astrophysicists后面有一個由分詞短語充當的定語“working with ground?based detectors at the South Pole and balloon?borne instruments”。

　　譯文：天體物理學家使用南極陸基探測器及球載儀器，正越來越近地觀測這些云系，也許不久會報告他們的觀測結果。

　　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年真題)

　　分析：此句為not...but連接的并列復合句。在not和but后分別有一由that引導的表語從句。譯文：這并不是說面包師或賣肉者所用的磅秤和化學家所有的天平在構造原理和工作方法上存在多少差別，而是說與前者相比，后者是一種更為精密的儀器，因而在計量上必然比前者準確得多。