undergoon Academic Word Listalso onCEFR Upper intermediate (B2)? CEFR Advanced (C1)? experimentar,sufrir undergo undergo(verb) experimentar,sufrir undergoes undergoes(verb) experimentar,sufrir undergoing undergoing(verb) experimentar,sufrir undergone undergone(verb) experimentar,sufrir underwent underwent(verb) experimentar,sufrir Forms verb undergo undergoes undergoing undergone underwent