element: applies to any such part and oft. connotes inreducable simplicity: basic ~ of the Gothic novel.


component: stress separate identity and distinguishable character of the elements: able to identify every ~ of his firearm.  


constituent: stress essential and formative relationship of the elements, substances and qualities TO the whole: analyzed the ~ of the district.


ingredient: applies to any substances that can be combined to form a mixture that has qualities  that may be different from its constituents: the ~ of a cocktail.


factor: applies to any element or constituent whose presence helps to perform a certain kind of work or produce a particular result: price was a ~ in her decision to buy.


element元素：简单不可再分的, component组件: 强调独立的个体和属性, constituent: 强调基本和形成总体(constitution宪法)，ingredient配料: 和最终混合物性质不同，factor因素: 任何帮助实现目的元素、组成。


记忆方法： 1） 首字母联想，EC CIF==>CE ICF: Chinese Economy Industry Commerce Farming: 中国经济由工业、商业、农业组成。

                 2）元素的意思是复合体的一部分mean one of the parts, substances, or principles of a compound or complex whole.