V can be a single vowel, diphthong, or triphthong. Their vowel system includes seven basic vowels, three rhotic vowels, six diphthongs, and one triphthong. That is, when a monophthong changes into a diphthong or triphthong (Monophthongization). In addition, there exist 15 diphthongs and one triphthong in the language of Northern Qiang. Some linguists use the terms "diphthong" and "triphthong" only in this phonemic sense. A syllable requires a vowel (or diphthong or triphthong) to appear in the middle. If the appearance of the sound produced a triphthong, the middle vowel dropped out. The words "cure, pure, sure" may be pronounced with a triphthong . In the case of vowels, the terms diphthong and triphthong are used instead of 'contour'.