expense

1.说“（做某事的）经费”习惯用复数形式，如travelling expenses和development expenses。

2.at the expense of后面接的词通常是表示被损失或耗费的东西。例如：He walked the whole distance at the expense of his health. 但有时也接表示被经历的事物的词。例如：He walked the whole distance at the expense of much weariness. cost 1里的各例句里的cost改作expense也可以。