Complex sentence: In Modern Greek, all vowels and consonants are short, many vowels and diphthongs that used to be pronounced distinctly are pronounced as (iotacism), some of the stops and glides in diphthongs became fricatives, and the pitch accent changed to a stress accent.
Split into simpler sentences: In Modern Greek, all vowels and consonants are short--many vowels and diphthongs once pronounced distinctly are pronounced as (iotacism). Some of the stops and glides in diphthongs have become fricatives, and the pitch accent has changed to a stress accent.