three years ______ ______ since they left here.他们离开这儿3年了
问题描述：
three years ______ ______ since they left here.他们离开这儿3年了
答
填has passed~
since前面应该用完成时。。
后面用过去式~
答
Three years ___has___ __passed____ since they left here.