请修缮这段文字要求表达要清晰语法要准确。Case analysis method refers to the study of typical cases in the research field which combines theoretical and practical research methods Through the analysis of public service ann

The case analysis method involves the examination of typical cases within the research field, which integrates theoretical and practical research approaches. In this paper, the study of public service announcement language is utilized to combine theory and practice. Specifically, representative examples of public service announcement language are selected and analyzed through the application of speech act theory.