Though administration officials said significant progress was made , especially on the economic front , the session also underscored the intractable nature of a long list of grievances between the world ' s richest country and its fastest rising rival 虽然官方说已经取得了明显的进步,特别是经济冲突,但也同时强调了两国之间存在着一长串难于解决的问题的事实。