my uncle has joined the army since 1995

two months has passed since he joined the army It is 3 years since he joined the army.为什么用is不用has been my uncle told me,"l joined the army in 1995."变为间接引语 my uncle joined the army two years ago（保持原句意思） My brother has joined the army for three years.(同义句改写) My elder brother _____ the army for three years A.has joined ____ four years since I joined the Army. it has been 5 years since he joined the army 是表肯定还是否定呢 求教英语大 看到一句It is 3 years since he joined the army.和一句It has been th It is three years since he joined the army.为什么是用joined而不是用ha It is said _______ he has joined the army. 用since的话,本句应该是：It is ten years since he joined the army.