no other than 是一般语气，none other than 则强调出人意料的人或事
～It was no other than his mother. 那就是他的母亲。
～He called together his employees and announced that the manager was none other than his son. 他把所有的员工召集到一起，宣布的经理不是别人，竟然是他的儿子。
追问老师，两句话的was是否可以改成is，有没有影响？
追答第一句可以，不过应该译作 “这就是 ...”，而不是 “那”。
第二句的主句是过去时态，从句应该与主句时态保持一致。
追问谢谢老师