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(gè)或幾個(gè)同等成分，這種結(jié)構(gòu)稱為并列結(jié)構(gòu)。連接的同等成分可以是動(dòng)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(jié)構(gòu)，每個(gè)并列結(jié)構(gòu)中各有一個(gè)when引導(dǎo)的時(shí)間狀語從句。在第二個(gè)時(shí)間狀語從句中有一個(gè)what引導(dǎo)的主語從句。

　　譯文：一般說來，當(dāng)要測(cè)定的特征能得以十分精確的界定，測(cè)試的就比較佳；反之，如果所要測(cè)定和預(yù)測(cè)的東西得不到明確的界定，那么測(cè)試的效果就比較差。

　　例2Astrophysicists working with ground�瞓ased detectors at the South Pole and balloon�瞓orne 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(dǎo)的并列結(jié)構(gòu)，兩個(gè)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(gè)由分詞短語充當(dāng)?shù)亩ㄕZ“working with ground�瞓ased detectors at the South Pole and balloon�瞓orne instruments”。

　　譯文：天體物理學(xué)家使用南極陸基探測(cè)器及球載儀器，正越來越近地觀測(cè)這些云系，也許不久會(huì)報(bào)告他們的觀測(cè)結(jié)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(fù)合句。在not和but后分別有一由that引導(dǎo)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(xué)家所有的天平在構(gòu)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(jì)量上必然比前者準(zhǔn)確得多。