Assertion: diphthong's vowel | /r/CapableOf | combine with each other
Facets:
Source sentences:
text: o or when the two vowels combine with each other, in which case either the i or u may remain unstressed.
text: A diphthong is formed when an unstressed i or u combines with another vowel (a, e, o) or when the two vowels combine with each other, in which case either the i or u may remain unstressed.