sentence: While visiting Wawel Royal Castle one should not miss seeing Dragon 's Den - a cave under the Castle , where , according to the oldest legends , the dragon of Wawel lived .
modified: While visiting Wawel Royal Castle one can not omit seeing Dragon 's Den - a cave under the Castle , where , according to the oldest legends , the dragon of Wawel lived .
transformation: VERB:TENSE, VERB