rigid: implies uncompromising inflexibility: the school's admission standards are ~.    （compromise  1、双方妥协折中和解an agreement or settlement of a dispute that is reached by each side making concessions，如eventually they reached a compromise他们最终达成了和解，如the secret of a happy marriage is compromise婚姻美满的秘诀在于互让  2、单方妥协，如sexism should be tackled without compromise处理性别歧视决不能妥协）     flexible灵活指受外力后变形，避免被折断，inflexibility和uncompromising意思相同，没有译出        （rigor泛指严格，如严格严厉严谨严密严酷，如the crime will be treated with the full rigor of the law这一罪行会严格审理，如academic/scientific rigor学术/科学严谨性，the analysis lacks rigor该分析缺乏严谨性，如the rigors of a harsh winter/war严酷的冬季/战争）


rigorous: implies the imposition of hardship and difficulty: the ~ training of recruits.      （rigorous指让人困苦的rigid，即比rigid程度重，如rigorous discipline/training严酷的纪律/训练）  


strict: emphasizes undeviating conformity to rules, standards, or requirements: their doct put them on a ~ diet.    很常用，解释请记下来


stringent: suggests restrictions or limitations that curb or coerce: the judge's ruling is a ~ interpretation of the law.  这个词容易写错，前边是string        （curb路边的侧石，限制； coerce暴力强迫to force by violence or intimidation，如coerced into selling the business被迫出售生意）            如stringent laws严苛的法律/stringent budget拮据的预算


rigid严格: 指标准不放松不妥协，rigorous严酷: 严格到令人困苦，strict严格: 指始终遵守规则标准要求，stringent严苛: 表示约束限制等强制苛刻


记忆方法: 1）首字母RRSS想成诗人杜甫"晚节渐于诗律细"<==严格              "严"的意思是"不放松"，原本上边还有两个口，形容坚持态度坚持，好像在反复叮咛

         2）严格的意思是mean extremely severe or stern.       severe和stern都表示严格，即不放松标准，是2019-04-10 严格severe-ascetic组前两个词，其中severe泛指严格，stern特指人脾气性格等严格，如a stern judge/face一位严格的法官/严肃的脸庞