[译] 她久病不治而亡。
[误] She died after a long disease.

[正] She died after a long illness.
[注] disease 与 illness 是同义词，但是 illness 指患病的状态或期间，disease 指具体的某一疾病，如 a chronic disease（一种慢性病），a fatal disease（致命的疾病），但是不能说 a long disease。汉语中“久病而亡”实际指经历长久生病状态而病亡，所以应该用 die after a long illness。