thus often found before the vowel , as in cube – which was in some cases modified to or before (historical) , as in cure, or weakened to or as in argument. They also occurred in words ending in -ion and -ious, such as nation and precious. This change from to , which had occurred in London by the end of the 17th century, did not take place in all dialects. A few dialects, notably in Wales, as well as in some parts of northern England, New England, and the American South, still retain a (falling) diphthong where standard English has – these dialects therefore lack the clusters with and have not been subject to the reductions described here. The diphthongs or are most commonly indicated by the spellings eu, ew, uCV (where C is any consonant and V is any vowel), ue and ui, as in feud, few, mute, cue and suit, while the historical monophthong is commonly indicated by the spellings oo and ou, as in moon and soup. Yod-dropping Yod-dropping is the elision of the from certain syllable-initial clusters of the type described above. Particular cases of yod-dropping may affect all or some of the dialects that have the relevant clusters. The change of to in these positions (as described above) produced some clusters which would have been difficult or impossible to pronounce, which led to what John Wells calls Early Yod Dropping in which the was elided in the following environments: After , for example chute , chew , juice After , for example yew (compare in some conservative dialects) After , for example rude After stop+ clusters, for example blue The previously mentioned accents that did not have the → change were not subject to this process. Thus, for example, in much Welsh English pairs like chews/choose, yew/you and threw/through remain distinct: the first member of each pair has the diphthong , while the second member has : chews , choose yew , you threw , through Conversely, an initial does not appear in Welsh English before in words such as yeast and yield. Many varieties of English have extended yod-dropping to the following environments if the is in the same syllable as the preceding consonant: After , for example suit After , for example lute After , for example Zeus After , for example enthuse Yod-dropping in the above environments used to be considered