สำนักงานราชบัณทิตยสภา

142  The Journal of the Royal Institute of Thailand Volume IV - 2012 Findings related to adjective in fl ection Although in fl ection for adjectives is relatively more straightforward than both noun and verb in fl ection in the English language, it was also found to include two main variations and some spelling variations for comparative and superlative forms using –er and –est af fi xes. For comparative and superlative forms, adjectives are formed by adding the suf fi xes –er and –est respectively. The rules of spelling for words ending with –e or a consonant preceded by a vowel are followed. If the adjective has two or more syllables, the comparative and superlatives forms are generally made by adding more or most before the adjective. Some two-syllable adjectives follow both of the two rules by either adding –er / -est at the end or using more or most before. Also, there are a small number of adjectives that do not follow either of these in fl ectional patterns and thus are considered to be irregular. It can be concluded that adjective in fl ection in English is also more complicated than following simple rules of grammar. Conclusion The main fi ndings of the study showed that in fl ectional variation in the English language is signi fi cant, especially for plural noun in fl ection. Other types of in fl ection are also rather complicated. Thai students are not normally exposed to these variations, even when they study English outside of their regular school programs. Variations in in fl ection are not focused on during instruction and practice of its use then is minimal. In addition, an in fl ectional language or the concept of a changing process is dif fi cult for Thai students. They are not familiar with the different environment of in fl ected nouns, verbs and adjectives, because there is no in fl ection occurring in the Thai language: there is no plural form of nouns, varied verb form in present or past participle, or a comparative and superlative of the adjective form in the Thai language. As a result they suffer from interlanguage interference and their development of accuracy is negatively affected. Furthermore, in fl ection and the various linguistics are interlinked, for example, the phenomenon at the phonological level is affected by English in fl ection, as in the sound change from a plural noun morpheme, possessive noun morpheme and a third person singular verb –s can be in fl ected to one of three possible phonemes /s/, /z/, and In fl ections in English Nouns, Verbs, and Adjectives