用since的话,本句应该是：It is ten years since he joined the army.用since的话,本句应该是：It is ten years since he joined the army.那本句改为It was ten years since he[ ]the army.怎么填
问题描述：
用since的话,本句应该是：It is ten years since he joined the army.
用since的话,本句应该是：
It is ten years since he joined the army.那本句改为It was ten years since he[ ]the army.怎么填
答
had joined