It is the first time that we travel. 在这个定语从句中

It is the first time that we travel. 在这个定语从句中 it is the first time that 是状语从句还是定语从句,that可省略吗? it is time that 从句 那这个从句到底属于是什么从句啊?如果是定语从句,那time在从句中做什么成分? it is the first time that i have been here 是定语从句么?that做谁的宾语? it is the first time that是主语从句吗 IT IS THE FIRST TIME THAT 句型是什么从句 It is the first time that从句做什么成分 it is/was the first time +that+clause中从句用什么时态? 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 this is first time that i take the plane..是定语从句吗? It is the first time that .这个句型中后面一定要跟完成时? This/It is the first/second … (序数词) time + that 从句 属于什么从句?