IT IS TIME THAT WE LEFT 书上说这是定语从句 为什么代词是THAT而不是WHEN

IT IS TIME THAT WE LEFT 书上说这是定语从句 为什么代词是THAT而不是WHEN the time 后jia定语从句是用关系代词that还是用关系副词when? it is the first time that 是状语从句还是定语从句,that可省略吗? It's time that we collected our reports.是同位语从句还是定语从句? it's time that you went to school 为什么是定语从句,关系代词在从句中不做任何成分呀 It is the first time that we travel. 在这个定语从句中 指导书上说that was where we camped last time是一个定语从句,可是表语从句不应该是 wh It is such an interesting book that we all like it.为什么不是定语从句 it is the last time that i shall come here to help you 是定语从句 为什么是It is said that 而不是It said that It is the museum that we visited last year.是定语从句还是强调句? it is the first time that i have been here 是定语从句么?that做谁的宾语?