un piano y una pizarra
un piano y una pizarra ?
u n WORD_BOUNDARY p j a n o̞ WORD_BOUNDARY i WORD_BOUNDARY u n a WORD_BOUNDARY p i s a r a WORD_BOUNDARY
u n WORD_BOUNDARY p i a n o WORD_BOUNDARY y WORD_BOUNDARY u n a WORD_BOUNDARY p i z a r r a WORD_BOUNDARY ? WORD_BOUNDARY