Which preposition to use with diphthongization

within Occurrences 1%

Other combinations of three vowels may be analyzed in a similar way, as may also combinations of more than three vowels, e.g. creíais, etc. B. SYNALEPHA Between the contiguous vowels of separate words there may occur synalepha (which corresponds to diphthongization within a word), or hiatus (which is similar to diaeresis within a word).

Which preposition to use with  diphthongization