There are many of phonetic change ways in language:assimilation,dissimilation,deletion,epenthesis ,and metathesis. Assimilation is a process of making a sound more similar to its adjacent sounds in one or more features. Assimilation results from economy of effort ,that is,the pronunciation of a word or a group of words is made easier through adapting the " shape" of one or more segments to the phonetic evironment."For example,it is possible for a speaker to pronounce a velar n / n / instead of an alveolar / n / in the words "in case" [ Inkes]. This is because of the influence of the following velar stop / k/. More examples are listed below.