stupid: implies a slow-witted or dazed state of mind that may be EITHER congenital OR temporary: you're too ~ to know what is good for you.     (dazed头昏脑胀,茫然困惑恍惚: confused and unable to think clearly, often because of shock or a blow to the head: At the end of the interview I was dazed and exhausted面试到最后，我头昏脑胀，筋疲力尽)


dull: suggests a slow or sluggish mind such as results from disease, depression or shock: monotonous work that left his mind ~.


dense: implies a thickheaded imperviousness to ideas or impressions: was too ~ to take a hint.


crass: suggests a grossness of mind precluding discrimination or delicacy: a ~, materialistic people.


dumb: applies to an exasperating obtuseness or lack of comprehension: too ~ to figure out what is going on. (exasperating: 让人不耐烦恼火Hardie could be exasperating to his colleagues哈迪有时让他的同事不耐烦恼火)


stupid愚蠢迟钝: 反应慢,总感觉困惑恍惚,先天或暂时，dull迟钝: 反应慢，由于疾病压抑震惊(depression抑郁即严重压抑)，dense也是愚蠢迟钝: 愚蠢迟钝(等于stupid，dense基本意思是稠密，thick也是稠密，impervious无法穿过的，这些词很形象，好像头脑愚钝到什么东西都进不进去)，crass愚钝粗糙:  头脑愚钝粗糙不懂鉴别不精细（和gross词形含义接近一起记，另外还表示没同情心），dumb: 让人不耐烦烦燥的愚钝和缺乏理解能力。


记忆方法：1）首字母SDDCD重排成Da Da De Chun Shi大大的蠢事<==迟钝的人容易做蠢事（应该多跑步？）


          2）口语中的asshole让人讨厌的人，解释是dishonest, incompetent and stupid.        



          3） 迟钝的意思是难以领会观念印象 mean lacking or seeming to lack power to absorb ideas or impressions.