By the time you come back next year, our son will be 8 years old.
到你明年回来的时候，咱们的儿子就8岁了呀！
难道这里的will be 8 years old 用错了吗？非得用
will have been 8 years old 吗？
关于by the time~1.表示将来的时间。主句用将来完成时，而从句用一般现在时来表示将来的动作。如:I will have finishied the work by the time my father comes back.2.表示过去的时间。主句用过去完成时，而从句用一般过去时。如：He had built a lab f
