新概念2中第54课中的this time it was the postman这里为什么用the?

it was the first time 后面为什么要用过去完成时 this was the third time they()china.为什么括号中填had visited,this+ It's spring time already.这里为什么用spring time 而不用the spring 新概念二第56课：Built in 1885,it was the oldest car taking part. it was the third time i was late this week.it was 后面什么用法? i bought it when i was living in the china,为什么这里要用was living 新概念第二册中《Breakfast or lunch》中有句It was my aunt Lucy,为什么这里要用过去式 用It/This/That was the first time that...和no...until/till 分别造 Who's that at the door?____ is the postman.A.She B.This C.It 新概念英语第二册第18课中“My dog had taken it into the garden",为什么要用过去完成 It was the first time that I had gone abroad.用英语改写一下（新概念二册第三 As my father(leave)the house,the postman (arrive)这道题是新概念2第一单