effort
1.在用作“努力”解的时候，effort后面接不定式。例如：His effort to reform her at length succeeded. 在用作“作品”解的时候effort后面接at和动名词或名词，如This is his effort at depicting the peasants和His maiden effort at authorship was a long tale。
2.an effort是“一次努力”，efforts是“多次努力”，effort是“努力”，是抽象名词。在make后面只用an effort, efforts, every effort, many efforts等，不用effort。在without effort（不费力）或without great effort（不费大力）里只用effort，不用efforts。
但Effort has been made to...（不定式），Special effort has been made to...（不定式）和Effort has been directed to（介词）...都可以说，又make special effort to...（不定式）也可以说。
