Vowel whose quality does not change over the duration of the vowel is called a monophthong. Monophthongs are sometimes called "pure" or "stable" vowels. A vowel sound that glides from one quality to another is called a diphthong, and a vowel sound that glides successively through three qualities is a triphthong. All languages have monophthongs and many languages have diphthongs, but triphthongs or vowel sounds with even more target qualities are relatively rare cross-linguistically. English has all three types: the vowel sound in "hit" is a monophthong , the vowel sound in "boy" is in most dialects a diphthong , and
Types of rape above, when differing acts of rape are defined and typified, whether by popular convention, research of the subject, or otherwise, the results are often neither exclusive nor exhaustive in scope. Some instances may fit two or more definitions, while others may remain as yet undefined. One example of this are the following sub-classifications created by American researcher Patricia Rozee: Where they are not already typed above, many of these otherwise distinct forms could equally apply to other classifications (e.g. prison rape that is also punitive rape, war rape that is also theft rape, etc.) Types of rape Rape can be