He showed that, generally, any consonant from one of these groups could combine with consonants from any other group, but could not be used together with consonants from the same group.
hiː ʃˈoʊd ðˈæt, dʒˈɛnɚɹəli, ˌɛni kˈɑːnsənənt fɹʌm wˈʌn ʌv ðiːz ɡɹˈuːps kʊd kəmbˈaɪn wɪð kˈɑːnsənənts fɹʌm ˌɛni ˈʌðɚ ɡɹˈuːp, bˌʌt kʊd nˌɑːt biː jˈuːzd təɡˌɛðɚ wɪð kˈɑːnsənənts fɹʌmðə sˈeɪm ɡɹˈuːp.