否定句的非否定现象
否定句可以表示肯定的意义，有时甚至表示非常强烈的肯定意义。现将常见的表示肯定意义的否定句分门别类，作一归纳。
1．“can／could not be…＋enough”表示强烈的肯定。例如：
You can't be careful enough．（＝The more careful you are，the better．）你越小心越好。
We cannot be thankful enough to our teachers．我们对老师感激不尽。
2．“can／could not…too（over）”表示“无论怎样也不过分”。 例如：
A teacher cannot be too patient with his students．教师对学生越耐心越好。
We cannot over－emphasize the importance of physical exercise．体育锻炼的重要性，我们无论怎样强调都不过分。
3．“too…not to…”表示“太……不会不……”，具有肯定意义。例如：
He is too careful not to have noticed it．
他那么细心，不会没注意到这一点的。
Carrie was too worn by defeat not to feel that it was considerable．嘉利一再碰钉子后，不能不感到这是个好机会。
4．“never too…to”是对“too…to”的再否定，表示肯定。例如：
It is never too old to learn．活到老，学到老。
5．“not…for nothing”中，“not”用来否定“for nothing”，从而加强了谓语的肯定意义。例如：
Believe me，he did not fly into such a rage for nothing．请相信我，他勃然大怒是有原因的。
I saw it in your eyes when I first beheld you：this expression and smile didnot——did not strike delight to my inmost heart for nothing．（Charlotte Bronte）我第一次看见你时，就在你的眼睛里发觉了这点：这表情和微笑使我的内心深处感到这样欢乐，不是——决不是无缘无故的。
6．“nothing if not”表示“极其”，含强烈的肯定意义。例如：
He was nothing if not clever．他很聪明。
The situation is nothing if not fine．形势好极了。
7．“nothing less than”表示“完全是”。含义是肯定的。例如：
That's nothing less than a miracle．那完全是一个奇迹。
What he said was nothing less than a lie．他说的纯属谎言。
8．“nothing but”表示“只有；只不过”，含肯定意义。例如：
Don't worry about my illness；what I need is nothing but a few days'rest．不要为我的病担心，我只要稍微休息几天就会好的。
9．“no”的否定意义很强，和具有否定意义的名词连用，表示强烈的肯定。例如：
She is no fool．（＝She is very clever．）她决不是傻瓜。
There is no question that Dr．Tom Brown was in London in 1768．毫无疑问，汤姆·布朗医生1768年是在伦敦。
10．双重否定表示强调的肯定。例如：
Nobody had nothing to eat．（＝Everyone has something to eat．）
11．“not…until／till”表示“直到……才”，具有肯定含义。例如：
He did not come home until late in the evening．他直到晚上很迟才回家。
Not until midnight did it stop raining．直到午夜雨才停。
12．“否定词…＋ so＋ a．／ad．＋ as”结构从反面表示“最”，是一种强烈的肯定。例如：
None is so blind as those who won't see．（＝Those who won't see are theblindest．）没有比视而不见的人更瞎眼的了。
None are so deaf as those who won't hear．（＝Those who won't hear are thedeafest．）对别人的忠告置若罔闻的人才是聋子。
13．有些带否定词的短语，在句子使用时并不构成否定意义，却表示肯定。例如：
He would go as soon as not．他可太乐意去了。
As often as not the buses are late on foggy days．遇多雾天气时，公共汽车经常晚点。
14、否定的感叹疑问句常表示肯定意义。
Hasn't she grown？（＝She has grown．）她长大了。
Isn't it a fine day？（＝It is a fine day．）一个好天气。
Wasn't it a marvellous concert？（＝It was a marvellous concert．）一场非常精彩的音乐会。
15．以“Why don't you”和缩略形式“Why not”开头的疑问句往往表示邀请、建议、指导等，具有肯定意义。
Why don't you clean your teeth？（＝You should clean your teeth．）你该刷牙。
Why don't you make yourself an egg？（＝You can make yourself an egg．）你可以自己做个鸡蛋吃。
Why not ignore the remarks？（＝You can ignore the remarks．）别理睬这样的议论。
