attempt: stresses the initiation or beginning of an effort and often suggests the strong possibility of failure: will ~ to photograph the rare bird.  （effort努力implies the calling up or directing of energy by the conscious will, and may refer to both a single action or persistent activity有意识地使用力量，既可指一次性也可连续性的活动，如made the supreme effort and crossed the finish line first尽最大努力，率先越过终点，如he made no effort to hide his disappointment他毫不掩饰失望之情）


try: stresses effort or experiment made to test or prove something: ~ied several times to find a solution.   （test测试，是为了验证是否良好或可用to discover if something is good or usable，如she said it was a 'test' of his character她说那是为了'测试'他的人品）


endeavor: heightens the implications of exertion and difficulty and connotes a striving to fulfill a duty: ~ed to find survivors of the crash.


essay: implies difficulty but also suggests tentative trying or experimenting: had ~ed dramatic roles on two earlier occasions.  （tentative初步暂定试探性谨慎not definite or certain because you may want to change it later，如we made a tentative arrangement to meet on Friday我们初步暂定星期五见面，如tentative conclusions初步结论，a tentative greeting试探性的问候，暗示谨慎cautious，如I'm taking the first tentative steps towards fitness我试探性地开始实施健身计划）


strive: implies exertion against great difficulty and specifically suggests persistent effort: continues to ~ for a lasting peaceful solution.   这个词强烈褒义，解释也不难，建议把解释背下来


attempt试图: 指发起一次努力，多暗示失败，try尝试:  指发起试验性努力，为了测试证明，endeavor努力奋斗: 强调困难费力，表示为履行职责而努力奋斗，essay尝试: 指试探性地尝试较困难的事情，strive努力奋斗: 指长期努力克服巨大困难


记忆方法: 1）首字母ATEES排列成SEE AT去看<==努力   "努"意思很简单: "尽量使出力气"，如汉乐府的少壮不努力老大徒伤悲，如陶渊明的及时当努力岁月不待人；另外努还表示"突出"，如努嘴  

         2）努力的意思是为实现目标而努力mean to make an effort to accomplish an end.