Pro-Form(替代形式)

　　1．Pro-Forms for Noun Phrases (名词短语的替代形式)

　　2．Pro-Forms for Adverbials (副词的替代形式)

　　3．Pro-Forms for Predicate (谓语的替代形式)

　　4．Sentence / Clause Reference (句子或从句的替代形式)