introductory
adj.
c.1600, from Late Latin introductorius, from introduct-, past participle stem of introducere "to lead in, bring in" (see introduction). Also used in English from c.1400 as a noun meaning "introductory treatise or textbook."
〔蒋〕[duc，duct=lead引导，-ory形容词后缀，…的] 介绍的，导言的