disability，inability
这一对词都表示无能之意，但涵义有细微的差异。
Disability着重表示因受伤而变残废所引起的无能（lacking ability caused by injury）或因天生的缺陷而导致的无能（inherent defect）；用于法律方面，它表示不够资格、不合格（legal disqualification）之意。例：
He has a disability pension because he lost his legs while he was in the army．
他领取伤残抚恤金，因为他在军队服役时失去了双腿。
He was always cheerful in spite of his disability．
他虽然有残疾（残废），但心情一直很愉快。
Inability 着重表示缺少能力或缺乏手段（lack of power or means）的意味。如：
His inability to undertake the work is due to his physical disabilities．
他没有能力承担该工作，是由于他的残疾。
Can you account for your inability to pay the debt？
您能否解释无法偿债的原因吗？