In 1857, when Mark Twain, born Samuel Clemens, became an apprentice river pilot, steamboating had been a part of the Mississippi scene for a quarter of a century.是什么意思_In 1857, when Mark Twain, born Samuel Clemens, became an apprentice river pilot, steamboating had been a part of the Mississippi scene for a quarter of a century.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句