and mouth became diphthongized, and other long vowels became higher: became (as in meet), became and later (as in name), became (as in goose), and became and later (in RP now ; as in bone). These shifts are responsible for the modern pronunciations of many written vowel combinations, including those involving a silent final . Many other changes in vowels have taken place over the centuries (see the separate articles on the low back, high back and high front vowels, short A, and diphthongs). These various changes mean that many words that formerly rhymed (and may be expected to rhyme based on their spelling) no longer do. For example, in Shakespeare's time, following the Great Vowel Shift, food, good and blood all had the vowel , but in modern pronunciation good has been shortened to , while blood has been shortened and lowered to in most accents. In other cases, words that were formerly distinct have come to be pronounced the same – examples of such mergers include meet–meat, pane–pain and toe–tow. Controversial issues Velar nasal The phonemic status of the velar nasal consonant is disputed; one analysis claims that the only nasal phonemes in English are and , while is an allophone of found before velar consonants. Evidence in support of this analysis is found in accents of the north-west Midlands of England where is only found before or , with sung being pronounced as . However, in most other accents of English sung is pronounced , producing a three-way phonemic contrast sum – sun – sung and supporting the analysis of the phonemic status of . In support of treating the velar nasal as an allophone of , claims on psychological grounds that did not form part of a series of three nasal consonants: "no naïve English-speaking person can be made to feel in his bones that it belongs to a single series with m and n. ... It still feels like ƞg." More recent writers have indicated that analyses of as an allophone of may still have merit, even though may appear both with and without a following velar consonant; in such analyses, an underlying that is deleted by a phonological rule would account for occurrences of not followed by a velar consonant. Thus the phonemic representation of sing would be and that of singer is ; in order to reach the phonetic form and , it