1.apology通常不用作抽象名词，如可以说make an apology, make apologies, make his apology（或apologies）等，却不说make apology。但a letter of apology, a word of apology等表达方式里的apology不可改作apologies。in apology for里也必须用单数形式。例如：In a little while she smiled at us again, as though in apology for her show of temper.
2.apology的复数形式apologies在习惯上常用，却并没有“多次道歉”的意思，如make (his) apologies, accept my apologies, with apologies for...等表达方式都没有多次的意思。
