2.3 Previous Studies on Passive Voi

2.3 Previous Studies on Passive VoicePassive voice has been analyzed by many linguists from different schools. To conduct this study, previous corpus-based studies of passive voice at home and abroad will be firstly introduced in brief.However, before that, this section will focus on related studies of passive voice in academic writing from other perspectives.Traditionally, the linguists often conducted studies of passive voice in comparison with active voice concerning their structures and semantic meanings. In their opinion, the information of the passive constructions should be interpreted out of a transformation from their corresponding active structures(Biber et al.,2000). Jespersen(1924)analyzed the syntactic forms of passive voice, while he did not make a further analysis from semantic or pragmatic perspective.Palmer(1965)indicated that active voice was derived from passive voice, which involved inversion of subject and object, and the copula verb be, the past participle and the preposition by are added into the passives. However, he did not explain some situations, where active sentences cannot be transferred into passives. Granger(1983)noted that the existence of a passive structure did not necessarily indicate the existence of a coresponding active structure and vice versa.On the whole, traditional linguists were trying to give a full definition of passive voice. Afterwards, traditional linguists paid attention to the passive constructions and the features of these structures(Siewierska, 1966). On the basis of previous studies, Quirk et al.(1985) proposed a more detailed conclusion of transformation