____ four years since I joined the Army.

____ four years since I joined the Army. it is four years since I joined the army.这里的is,为什么不用was呢? --four years since I joined the army.A.There was B.There is It is four years since I joined the army.啥意思 Four years()since I ()the army 求分析 Three years ____ ____ since he joined the army 填have passed It is three years since I joined the army.改成完成时态 I ____four years since I joined the army.A.There was B.There i 1.It is two years ＿I joined the army.A.before B.since C.that It __four years since i joined the army.这里的is,为什么不用was呢? It is three years since he joined the army.为什么是用joined而不是用ha was two years ___ i joined the army.