Abstract：In the study of EFL acquisition, error analysis is crucial for English language learning and teaching. English passive is a very complex sentence form in English grammar. It is unavoidable for Chinese learners to misuse it because of the differences between English and Chinese.
The present study focuses on the unmarked English passives, one kind of English passive voice’s terms, constructions errors in the interlanguage of Chinese EFL learners. On the basis of the theories of interlanguage and error analysis, this dissertation tries to take the error correction and point out the causes of errors, and in–depth study of error treatment, hoping to give suggestions on avoiding errors are given from different aspects. It is believed that the findings in this study are helpful in the mastery of English passive voice and the understanding of its application, thus facilitating learning and teaching of the English language.
Key Words: unmarked English passives; error analysis; interlanguage; error correction; error treatment