It is three years ( ) we saw each other last year.括号中应填since

It is three years ( ) we saw each other last year.括号中应填since It's three years since we saw each other last time = We ____ (it is ） four years since we last saw each other.这句话括号里为什么不是 it's been six years since we last saw each other是个什么从句? ‘It's been six years since we last saw each other’怎么翻译? It _(be)five years since we last saw each other. how many years has it been since we last saw each other? it is almost five years （）we saw each other last time It is almost five years ___ we saw each other last time. It __ a long time since we last saw each other 一道初一英语连词成句many,it,is,they,years,since,other,time,saw,each,la five years ___ ____since we saw each other last time