mindmap root((预备)) preliminary refers to what must be done or prepared or acquired before some other state or activity becomes possible: held a ~ discussion to set up the agenda for the meeting. introductory refers to the first steps in a process and usually applies to what sets something （such as an action, a work, or a process） going: the speaker's ~ chapters established his point of view. preparatory comes close to preliminary in meaning but emphasizes preparedness for or against what is expected to ensue: take ~ protective measures against a predicted hurricane. prefatory usually implies a desire on the part of someone to prepare others for such activities as hearing, action, or understanding, or process: made some ~ remarks before introducing the speaker.