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 measured or predicted can not be well defined. (1995年真題)
　　例2Astrophysicists working with ground�瞓ased 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)
　　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)