解释两个句子It was five years since I lerned English.和It was five

解释两个句子It was five years since I lerned English.和It was five it is five years since we began learing English 为什么是it was it is five years since we began learing English 为什么不是it was 为什么选B.不选A.----It's five years since I was a singer ----Not r It is five years since we began learning English It --- five years since he left for Beijing. A.was B.had bee It ____ five years since he has left for Beijing.A.was B.has It ___ five years since he left for Beijing.A.was B.had been 1. It `s five years since I _________(study)English. 2.He al When i was five years It _____ five years since I came to this city. It (be)five years since I (ride)a bike.