continual: implies a close or unceasing succession or recurrence: ~ showers the whole weekend.        （cease停止may imply gradualness and a degree of finality逐渐并最终停，而stop一般表示突然停止，如by nightfall the fighting had ceased入夜战斗逐渐停止了下来， 如her exploits never cease to amaze me她的壮举总是让我惊奇，同样ceaseless和unceasing表示没有最终停止，不过中间可能偶有停歇，如ceaseless struggle/noise不断的努力/不停的噪声，unceasing support/efforts不懈的支持/努力。下一词条中的uninterrupted表示连"interrupt短暂打断"都没有，即毫不停歇的，continual和continuous的区别就是unceasing和uninterrupted的区别）  close密集  succeed继承接续     阵雨；淋浴；大量给与    


continuous: usually implies an uninterrupted flow or spatial or temporal extension: the ~ roar of the falls.      又如continuous efforts/advances/tense/supply不断努力/进步/[语法]进行时/持续供应


constant: implies uniform or persistent occurrence or recurrence: lived in ~ pain.      如the temperature must be kept constant温度必须保持恒定，如constant love始终如一的爱，a constant friend忠实的朋友，作为名词表示数学或物理中的常数常量恒量


incessant: implies ceaseless or uninterrupted activity that is viewed as undesirable or distasteful: the ~ quarreling frayed her nerves.    incessant demands不停的要求


perpetual: suggests unfailing repetition or lasting duration: the fear of ~ torment after death.     可以褒义或贬义，如a perpetual rose/calender/war/youth/search四季开花的蔷薇/万年历/不停的战争/永远的青春/毕生的寻求          词根PER表示through贯穿通过，所有per都表示through，PET表示to seek寻求==>perpetual始终寻求           last表示比同类使用寿命长，下一词条的endure暗示抗侵蚀，都表示to continue for a long time不必细分


perennial: implies enduring existence often through constant renewal: a ~ source of controversy.     也可用于褒贬，词根PER表示through贯穿通过，ENN/ANN表示year年==>perennial穿过整整一年的==>常年不变的，如perennial ice and snow终年不化的冰雪，如perennial youth/herb/river/crisis青春常驻/多年生的草/四季不枯竭的河流/一再出现的危机    


continual断续: 指偶有停歇地接续重复，continuous持续: 通常指毫不停歇，constant恒定不变: 指持续一致，incessant不停(贬): 用于不喜欢的事物，perpetual永久: 表示不停重复持久存在，perennial常年: 同上


记忆方法: 1）首字母CCCIPP排序成PICC PC中国人保赔偿<==持续不断

         2）练习一下

         3）持续的意思是继续发生不停止mean characterized by continued occurrence or recurrence.首字母CCCIPP排序成PICC PC中国人保赔偿<==持续不断      （基础词continue继续applies to a process going on without ending泛指一个过程一直进行而不结束，如the stock market will continue to rise股市会继续上升，如the forest continues for miles这树林延续数里，如continue the revolution继续革命，如to be continued待续）