obscure: implies a hiding or veiling of meaning through some inadequacy of expression or withholding of full knowledge: the poem is ~ to those unlearned in classics.  (hide隐藏,veil掩藏既可有意也可无意，veil面纱朦胧)   (withhold保留不公布，常表示合理: withheld information from authorities当局保留信息 )


dark: implies an imperfect or clouded revelation often with ominous, mysterious, or sinister overtones: muttered ~ hints of revenge.


vague: implies a lack of clear definition or formulation because of inadequate conception or consideration: made ~ promises of reimbursement.  报销  (conception构思: 是想象构造concept概念的过程，常指特定独特的概念)


enigmatic: stresses a puzzling, mystifying quality: left behind ~ works on alchemy.   (the enigmatic smile of Mona Liza蒙娜丽莎的神秘微笑，形容她微笑几乎千篇一律用enigmatic)  


cryptic: implies a purposed concealed meaning and often an intent to perplex or challenge: a ~ message only a spy can decode.  


ambiguous: applies to a difficulty of understanding arising from the use, usually inadvertent, of a word or words of multiple meanings: an ~ directive that can be taken either way.   (还形容颜色,如瞳孔是黑色褐色,海水是蓝色绿色,可以说the color of the eye (or the sea) is ambiguous难判断)     (inadvertent没有意识到,疏忽，如an inadvertent error一个疏忽错误)


equivocal: applies to the deliberate use of language open to differing interpretations with the intention of deceiving or evading: the prisoner would give only ~ answers.


obscure晦涩: 表示意思隐蔽(hiding,veiling of meaning)，因为表达不充分或保留不说(to withhold full knowledge保留不说出全部)，dark黑暗:  形容表达得不清楚(imperfect,clouded relevation揭示)，有不祥神秘邪恶的意味 (overtone暗示意味=suggestion,connotation)，vague模糊: 表示没有清晰的定义形式，因为缺乏构思考虑，enigmatic神秘: 表示神秘难懂(puzzle基本词只能死记,表示难懂难解决)，cryptic加密: 故意隐藏含义(conceal故意隐藏但hide未必)，迷惑挑战别人，ambiguous有歧义难判断: 使用的语言可以有多种解释， equivocal: 指故意使用有多种解释模棱两可的语言，以欺骗或逃避。


记忆方法: 1）首字母DOVE ACE最好的鸽子?<==意思难懂     (ace扑克里的A,表示最好，如an ace film最好的电影，短语holds all the aces占尽优势China held all the aces in the war中国在战争中占尽优势，an ace in the hole王牌绝招technology is our ace in the hole科技是我们的王牌)


         2）难懂的意思是不能清楚理解mean not clearly understandable.