這一對短語都有“終于”、“最后”的意思,但涵義和使用場合有所不同.
At length 這個詞組共有三個意義： （1）長時間地.例如：He spoke at（great）length．（2）詳細(xì)地.例如：They treated the subject at length．（3）終于；最后.例：After flying for ten hours,they got to San Francisco at length．
作第三種意義使用時,at length與at last同義,但它們的內(nèi)涵卻有所不同.當(dāng)人們做某事時,遇到了困難,經(jīng)過奮斗,最后得以完成,在這種場合,我們用at last.如果在做的過程中,經(jīng)歷了很長的時間才得以完成,這時候,不論困難大小,都可用at length表示.為此,我們說,at last強調(diào)的是“經(jīng)過努力奮斗”；at length 強調(diào)的是“經(jīng)歷很長的時間”.通過下列例句的對比,不難看出它們之間的區(qū)別：
Before they climbed down the side of the cliff,they met with many obstacles,but they surmounted them at last．
從懸崖的側(cè)面爬下來之前,他們遇到了許多障礙,但終于把它們克服了.
In spite of every obstacle,they have at last arrived at the destination．
盡管障礙很多,他們終于到達了目的地.
After a voyage of five months,they at length arrived safe and sound．
經(jīng)過五個月的航行,他們終于安全抵達.
請注意,用length構(gòu)成的介詞短語很多,常見的有：
Hong Kong Exhibition Centre measures 200 metres in length．
香港展覽中心長達二百公尺.
They discussed this problem at great length．
他們非常詳細(xì)地討論了這個問題.
Yesterday I had my picture taken at the studio at full length．
昨天我在照相館拍了一張全身照.
They travelled through the length and breadth of the country．
他們走遍全國.