Three years ____ ____ since he joined the army 填have passed

Three years ____ ____ since he joined the army 填have passed ____ four years since I joined the Army. It is three years since he joined the army.为什么是用joined而不是用ha two months has passed since he joined the army It is ten years since he ____(join) the army 八下英语改错1、Since he joined the club,two years have passed.2、My He is a ____ .He joined the army last year. Three years _____(have) passed since he came here.填什么?为什么? 用since的话,本句应该是：It is ten years since he joined the army. It is three years since I joined the army.改成完成时态 I John joined the army three years ago.(用since或for改写） 怎么写. John joined the army two years ago等于___two years since he jo