ow as in ‘go’ | American English Pronunciation :the “o” in go was originally an /ɑː/, while the “o” in do and to was originally an /oː/. So they were always different to begin with, and even the Great Vowel Shift could do nothing about it, because different vowels shifted into different directions.
ow as in ‘go’ | American English Pronunciation
Go and do happen to be spelled the same because in Middle English, the time period when much of the current English spelling system was formed, their vowels were fairly similar (/ɔː/ and /oː/ respectively), and there are not as many vowel letters in the alphabet as there are vowel sounds in English. But they have never been pronounced the same ow as in ‘go’ | American English Pronunciation.