1. it’s been a long time since we left our junior middle school. since(conj) 自从，因为 (1)接时间点：如 i have stayed in that country since 1995. （要求：谓v.用现在完成时，而且须是延续性动词。） (2)接一段时间 + ago：如 they have lived in that house since two years ago. （要求：谓v.用现在完成时，而且须是延续性动词。） (3)接时间状语从句： i have loved her since i met her last time.
