英语中有些句子没有含否定式却表达了否定意义,这一情况通常被称为暗否定或隐藏否定 (concealed negation)。熟悉了这些常见的暗否定句子结构会有利于英语学习者对英语句子的理解，从而更好地掌握英语。常见的暗否定结构有以下一些形式:
一.有一些词或短语可起到表达暗否定的效果。
⒈句中用“the last、the least、the limit”等词组可表示强烈否定，意思是：“最不……”。例如：
You're the last one that I want to see in the world. （你是我最不愿见的人。)
He spoke ill of me, and that's the limit. (他说我的坏话，那真让人无法忍受。)
⒉ but for（要不是/倘若没有）后接名词或代词、but that（要不是/倘若没有）后面应跟从句，二者均表示虚拟的条件，谓语动词须用虚拟语气结构。
But for your help, I couldn't have succeeded.
But that you had helped me, I couldn't have succeeded.
要不是你的帮忙/如果没有你的帮忙，我是不会成功的。
⒊ anything but（决非,决不，一点也不），but后跟名词/代词/形容词，有强势否定之义。
My father likes anything but beef. (我父亲最不喜欢吃牛肉。)
The painting is anything but beautiful. (这幅画根本就算不上美。)
⒋ everywhere but 表示“决不在……”
He will work everywhere but in Shanghai. (他根本不愿意在上海工作。)
⒌ let alone“更不必说”
He can't ride a bicycle，let alone a motorbike. (他不会骑自行车,更别说摩托车了。)
二.有些连词也可以表达暗否定义，比较常见的连词有unless、since、before等。
⒈ unless 引导的从句，意为“除非”, 相当于if...not...
He never speaks unless he is spoken to.
＝He never speaks if he isn't spoken to. (如果别人不和他说话,他就不说话。)
⒉ since引导的状语从句中，若谓语动词为延续性动词且为一般过去式时，从句所表示的时间从动作终止或状态不再继续时算起,用否定翻译法翻译句子。
We've been out of touch since we lived together(自从我们不在一起住，就失去了联系。)
对比：It's 6 years since I graduated from Beijing University。
（我从北京大学毕业到现在已有6年时间了。）
⒊ before引导的状语从句也可以表达暗否定义
The audience had all left before the play finished. （戏剧还没有结束观众就已经走光了。）
Three months went by / on before Aqiao knew it. (不知不觉中阿巧度过了三个月。)
三.有一些比较结构也可表达暗否定。
⒈more...than...表同一人或事的不同性质或特征。
Lu Bu is more brave than wise. (吕布有勇无谋。)
⒉no+形容词/副词的比较级+than，对双方进行否定，意思为：并不比
Tom is no cleverer than his brother. （汤姆并不比他兄弟聪明．（一样笨/都不聪明．）
⒊“less+形容词或副词原级+than”结构表示否定的对比。
The results left us less than satisfied. （结果让我们不太满意。）
⒋用“still、much、even、 a little”等表示否定程度。
She hasn't cleaned her own room, still less mine.
(她自己的房间都没有打扫，更不用说我的了。)
对比：We should thank him for his advice, still more for his financial help.
（我们应该感谢他的建议，更要感谢他的资金援助.)
★ still more用于肯定句, still less用于否定句。
四.某些固定的结构也可以表达暗否定。常见的有“too...to...”相当于so...that...can't或not...enough to...
⒈ It was too difficult for us to work out the problem.
注意对比：He is too glad to receive your letter. （他收到你的来信非常高兴。）
⒉prefer ...to .../ prefer to do ...rather than do .../ would rather do…than do/ prefer doing rather than doing。宁愿…也不愿…
eg: ① The workaholics prefer to tire themselves out in work rather than sit doing nothing. (工作狂们宁愿累死在工作中也不愿无所事事。)
② The Red Army soldier would rather die than give in.
五.某些情态动词跟动词完成式也可表否定意义, 常见的有:
should have done (本应做而没做）
need have done（本需要做而没做）
could have done(本能够做却没有做/可能已做过)
would like to have done (本愿意已做过而没做)等。
① I would like to have gone to your birthday party last night， but I had to do extra work.
(昨天晚上我本来要参加你的生日晚会的，但因为加班而没有去成。)
②Our team could have won the football game if it had not been because of the absence of Jack.(要是杰克不缺席，我们就能赢那场球赛。)（实际上我们队没有赢。）
③As his best friend，you should have help him out.
(作为最好的朋友，你本应该帮助他摆脱困境的。) （实际没有帮助他。)
六.英语中有些词或短语在形式上是肯定，但却具有否定意义。常见的有：
“be inferior / second to， be junior to， fail to，differ, escape，keep from，desert， be blind to， be absent from， live up to， be short of， miss， deny， refuse， let alone， much／even / still less 等。
①I'm junior to Xiao Wang. (我没有小王年龄大。)
②The boss was blind to Tom's excuse. (老板对汤姆的借口置之不理。）
③He is second to everyone else in maths in Class 1.(他的数学在一班里是最差的.)
七.部分介词或介词短语表示暗否定，常见的表达暗否定意义的介词有：
above，under，over，below， beneath， beside， behind，past， against，except，beyond，from，far from，off，to， without， out of等。 一些介词和名词连用时所表示的暗否定能达到一定的修辞效果，如: beyond words (beyond description / praise), beneath notice，in spite of， instead of， out of work / power.
①This maths problem is beyond me.
②——Are you satisfied with the speech？
——No,far from it. I've never seen a more boring one.
