史无前例: there was no parallel in history.; be unprecedented in the nation's history; unprecedented in history; without parallel in history; without precedent in history 短语和例子史无前例的壮举 an unprecedent
前所未有: hitherto unknown; such as never previously existed; unprecedented 短语和例子前所未有的盛况 an unprecedentedly grand occasion; 遇到前所未有的困难 encounter greater difficulties than ever