Studies in the diachronic quantitative changes of English vowels

我们认为，在-ld、-rd、-nd等同调辅音群之前的重读短元音的拉长是由于元音数量的拉长，而不是由辅音群引起的，对于双音节词开音节中重读元音的拉长，我们假设有两个过程，即：一是重读元音的拉长，二是重读元音的拉长，三是重读元音的拉长，四是重读元音的拉长，四是重读元音的拉长，五是重读元音的拉长，六是重读元音的拉长，六是重读元音的这两个阶段即全元音的补偿性拉长和后一个元音的补偿性拉长，解决了元音拉长的后期缩短、拉长的周期性差异和拉长的方言差异等问题。

We ascribe the lengthening of stressed short vowels preceding the homorganic consonant clusters such as -ld, -rd, -nd to stretching of vowel quantity caused only by the following voiced obstruents but not by the clusters, whic leads us to make satisfactory explanations to the various problems involved in the lengthening in question.As for the lengthening of stressed vowels in open syllables of disyllabic words we assume a process of two stages, tha is, compensatory lengthening as an outcome of the change of unstressed vowels with full quality into schwa and also a compensatory lengthening caused by the subsequent loss of schwa, which enables us to solve several problems such as the later shortening of the lengthened vowels, the periodical differences of the lengthening, and the dialectal differences of the lengthening.