nullify: implies counteracting completely the force, effectiveness, or value of something: his critical insights are ~ied by tiresome puns.   （counteract表示互相抵消implies an opposition between two things that nullifies the effect of one or both，可见counteract和nullify互释，如poor eating habits will have a counteractive effect on any gains from exercise不良饮食习惯会抵消运动带来的好处） nullify常表示废除，如he used his broad executive powers to nullify decisions by local governments他利用自己广泛的行政权力废除当地政府所作的决定   pun双关


negate: implies the destruction or canceling out of one of two mutually exclusive things by the other: a relationship ~d by petty jealousies.  mutually exclusive互相排斥，如True和False是互相排斥的，如果某物是False，就一定不会是True，又如二进制里的1和0也是mutually exclusive，它们的存在都会"negate" the other one(of the two).


annul: suggests a neutralizing or a making ineffective or nonexistent often by legal or official action: the treaty ~s all previous agreements.  


abrogate: is like annul, but more definitely implies a legal or official purposeful act: a law that would ~ certain diplomatic privileges.   可见，表示官方法律的两个词都以a开头


invalidate: implies a making of something powerless or unacceptable by a declaration of its logical or moral or legal unsoundness: the absence of witnesses ~s the will.   （sound合理，指观点意见主张等合理有依据implies flawless reasoning and solid grounds，如a sound proposal for combatting terrorism打击恐怖主义的合理建议，在2018-06-07 合理valid-telling组中，基础词valid表示真实有效可接受，sound表示不但valid，而且有理有据 ）  又如invalidate a contract/marriage/test result使合同/婚姻/测试结果无效，注意是使无效，不是废除取消


nullify抵消废除: 指完全抵消效力价值，也常指废除，negate否定抵消: 指被互相排斥的二者之一否定(destruct毁灭cancel out取消)，annul废除: 表示通过官方法律行动，使抵消失效废除等，abrogate废除: 更明确表示官方法律行为，invalidate使无效: 使无效力或变得不可接受，因为存在逻辑道德法律上的错误


记忆方法: 1) 首字母重组为NANAI难捱(不易忍受)<==废除    

         2) 废除的意思是使不再有效存在mean to deprive of effective or continued existence. 首字母重组为NANAI难捱(不易忍受)<==废除   （deprive剥夺means to take something away，如this law will deprive us of our most basic rights这项法律将剥夺我们最基本的权利，如新四20篇they do not realize that they are deprived of the necessities of life他们没有意识到被(大城市)剥夺了生活必需）