prompt: Generate a sentence with "c1" difficulty and keywords: stump, throbs, mouth, tongue, black.
label: Its stump throbs in her mouth, while the tongue itself
  
  falls to the black earth trembling and murmuring,
  
  and twitching as it flings itself about,
  
  just as a serpent's severed tail will do;
  
  and with what little life is left it, seeks
  
  its mistress's feet.