would have done, 表示与过去事实相反的假设或结果。
我会很高兴和他见面的，但我没时间见他。I would have been happy to see him， but I didn't have time
你父亲如果还健在的话，他会为你骄傲的。If your father had still been alive， he would have felt very proud of you
can not too, could not too, 表示“无论怎样也不过分”。
穿越马路时，再怎么小心也不为过。You cannot be too careful when crossing the street
做实验越仔细越好。You can never be too careful in performing an experiment
can not enough, could not enough, 意为“无论怎么都不够”，表示强烈的肯定。
我对你感激不尽。I cannot thank you enough
你越小心越好。You can't be careful enough
too not to， 表示“太不会不”，具有肯定意义。
他那么小心，一定会注意到这一点的。He is too careful not to have noticed it
never too to， 是对 too to， 的再否定，表示肯定。
活到老，学到老。it 's never too old to learn
not for nothing， 中， not 用来否定 for nothing ，从而加强了谓语的肯定意义。
他学法律并没有白费。He didn't study law for nothing
请相信我，他勃然大怒是有原因的。Believe me ， he did not fly into such a rage for nothing
nothing if not， 表示“极其”，含强烈的肯定意义。
他很聪明。He was nothing if not clever
故事极其有趣。The story was nothing if not interesting
nothing less than， 表示“完全是”，有肯定的含义。
他说的纯属谎言。What he said was nothing less than a lie
他的粗心大意无异于犯罪。His negligence was nothing less than criminal
nothing but， 表示“只有；只不过”，含肯定意义。
我们只看见一大片水。We could see nothing but water
她除了听唱片什么也不做。She does nothing but listen to records
no 的否定意义很强，和具有否定意义的名词连用，来表示强烈的肯定。
她绝不是傻瓜。She is no fool
She is very clever
毫无疑问，史密斯先生就是老板。There is no question that Mr Smith is the boss
双重否定表示强烈的肯定。
每个人都有吃的。Nobody had nothing to eat
Everyone has something to eat
not until， not till, 表示“直到才”，具有肯定的意义。
昨晚12点以前，她一直在不停地工作。She didn't stop working until it was 12 o'clock last night
“否定词+ so + 副词 + as， 否定词+ so + 形容词 + as， ”结构从反面表示“最”，是一种强烈的肯定。
这次不像上次那么坏！it wasn't so bad as last time ！
没有比视而不见的人更瞎眼的了。None is so blind as those who won't see
有些带否定词的短语，在使用时并不构成否定意义，即表示肯定意义。
他非常乐意去。He would go as soon as not
很愿意，再乐意不过as soon as not
遇多雾天气时，公共汽车经常晚点。as often as not the buses are late on foggy days
往往，多半as often as not
否定的感叹句、疑问句常表示肯定意义。
这电影难道没趣吗？Isn't this film interesting ？
谁不喜欢看《红楼梦》呢？（人人都喜欢看《红楼梦》。）Who doesn't enjoy reading The Dream of the Red Mansion ？
以 why don't you do 和 why not do 开头的疑问句往往表示邀请、建议、指导等，具有肯定意义。
你为什么不介绍她给你父母认识？Why don't you introduce her to your parents ？
明天为什么不来看我？Why not come and see me tomorrow ？