the old man died 10 years ago同义句转换

Three months（have ）（passed ）since the old man（ died ）
句型上应该是这么填,不过为啥上面是10年,下面就变成3个月了啊

The old had died for 10 years.

应该是（It's）（ 10）（ years) since the old man died.