perseverance， persistence， tenacity， pertinacity
Each of these nouns means steadfast singleness of purpose, as in the pursuit of a goal, despite difficulties or obstacles.
这些名词都表示当在追求目标过程中碰着了困难或障碍时意向武断、专一的意思。
Perseverance suggests praiseworthy and enduring patience:
Perseverance 表明值得赞赏的、坚持到底的耐性：
“'Tis known by the name of perseverance in a good cause,—and of obstinacy in a bad one” (Laurence Sterne).
“大家都知道，毅力用于褒义而执拗用于贬义” （劳伦斯·斯顿）。
“Great works are performed, not by strength, but perseverance” (Samuel Johnson).
“伟大的作品不是靠力量而是靠毅力来完成的” （塞缪米·约翰逊）。
Persistence always implies firm resolve but may connote an obstinate, annoying quality:
Persistence 常表示武断的作法，但也可能表示固执、令人恼怒的品质：
“Persistence and courage are the most womanly no less than the most manly qualities” (Margaret Fuller).
“毅力和勇气就象适用男性一样适用女性” （玛格丽特·夫乐尔）。
Tenacity and especially pertinacity suggest stubborn, often perverse persistence:
Tenacity 尤其是pertinacity 意指执拗， 常常指刚愎自用的执拗：
“The Scots fought with desperate tenacity” (John Morley). “苏格兰人进行绝望的顽抗” （约韩·莫里）。
“Again and again . . . with the inexorable pertinacity of a child intent upon some object important to itself, did he renew his efforts” (Nathaniel Hawthorne).“一次又一次…凭着孩童对某些本身主要的目标所持有的不屈不挠的顽强，他重新开始了努力” （纳撒尼尔·霍斯隆）
perseverance persistence都含“坚持”的意思。
perseverance指“只管有困难、挫折, 但坚持不懈”, 如:
By perseverance the lame boy learned to swim.靠毅力这跛童学会了拍浮。
persistence 用于褒义, 指“意志武断, 不顾反对、阻力等的坚持”, 如:
By persistence many countries won freedom.通过坚持不懈的努力, 许多国家赢得了自由。
persistence 用于贬义, 则指“执拗”,如:persistence of a disease顽疾。
