son difíciles de qué
son difíciles de qué ?
s o̞ n WORD_BOUNDARY d i f i s i l e̞ s WORD_BOUNDARY d e̞ WORD_BOUNDARY k e̞ WORD_BOUNDARY
s o n WORD_BOUNDARY d i f í c i l e s WORD_BOUNDARY d e WORD_BOUNDARY q u é WORD_BOUNDARY ? WORD_BOUNDARY