illness, disease, ailment

虽然illness 和disease 常作同义词使用，但illness实际上指身体不适的状态或时期，disease才指各种具体的疾病。ailment则指常见病，不严重的病痛。 试比较：

He had a short illness six months ago.他6个月前小病了一场。

She had a rare eye disease.她患有罕见的眼病。

He is always complaining of some ailment or other. 他总是抱怨自己的身体这儿不舒服，那儿不对劲。