1． 含有否定意义的词汇和短语
　　以下列举的词和词组本身就具有否定的含义，因此无需用否定词。
　　介词against, beyond, but, except, without,...
　　形容词和动词absent, deny, differ, different, fail, free, ignore, miss, refuse, the last, used to, reluctant, lack, want,...
　　短语keep...from, protect...from, prevent...from, let alone, at a loss, in vain, instead of, out of the question, rather than, too...to, by no means, anything but,...
　　我们看以下例句：
　　1） Women fail to get the equal rights in some countries.
　　　　 在一些国家里妇女没有得到平等的权利。
　　2） This is by no means the best way to solve the problem of energy crisis.
　　　　这不是解决能源危机的最好的办法。
　　3） We should protect trees from being destroyed.
　　　　我们应保护树木，不让它们受破坏。
　　4） In old China we could not make a nail, let alone(make) machines.
　　　　在旧中国，我们连一个钉子都造不了，更不用说制造机器了。
2． 含有半否定意义的词语
　　barely, hardly, few, little, rarely, scarcely, seldom, not all, not everyone, not everything,...具有半否定的意义。例句：
　　1） We could hardly see any fresh vegetables in winter on market several years ago.
　　　　几年前在冬天市场上很难见到新鲜蔬菜。
　　2） These young people know little about how to choose good books to read.
　　　　这些年轻人几乎不知道如何挑选优秀的书籍来读。
3． 不含否定意义的否定结构
　　有些词和词组形式上是否定结构，但其含义是肯定的，比如：cannot but, can't help, no sooner...than, not...until, in no time, none other than, nothing but,等等。例句：
　　1） We can't but face the reality.
　　　　我们只有面对现实。
　　2） These old buildings will be replaced by modern apartment buildings in no time.
　　　　这些旧建筑将很快为现代化的公寓所代替。
4． 否定结构的倒装语序
　　我们有时为了强调而把否定词和词组放在句首，这时句子结构应倒装。例如：
　　1） On no account should we follow blindly.我们决不应当盲从。
　　2） No where has the world ever seen such great enthusiasm for learning as in our country.没有任何其他地方有我国这样高的学习热情。
五、 含有it的结构
考生病句：
　　1. As is known to all of us that science and technology play an important role in the
　　　　 development of society.
　　2. It is known to us, practice makes perfect.
正确表达：
　　1. It is known to all of us that science and technology play an important role in the
　　　　 development of society. (或:As is known to all of us, science...)
　　2. It is known to us that practice makes perfect. (或:As is known to us, practice...)
评议与分析：
　　例句1是93年12月六级考试11分作文的评分样卷句子，例句2选自97年1月四级考试作文。很显然，两个考生混淆了it和as的用法。如果用it作形式主语，后面的主语从句必须由that引起；如果用as，则后面不能用that，因为as是关系代词，代表practice makes perfect。
　　It 在英语中是个相当活跃的代词，在写作中我们常要使用它。以下几种用法应熟练掌握，并能灵活运用。
1．作形式主语
　　It is necessary for us to master a foreign language skillfully. It makes difference whether
　　 we could purify the air or not.
2.作形式宾语
　　We find it rather difficult to prevent people from doing that. Modern science has made it
　　 possible for babies to grow healthily and for people to live longer.
3.引导强调句
　　It is only by this way that we can achieve success. It was then that people began to realize
　　 the importance of controlling population.
　　从语法结构来看，上述的句子都不难，或者可以说是考生相当熟悉的。然而在写作考试中，多数考生缺乏运用自己已掌握的句式的意识，而以自己头脑中拼凑的中式英语取而代之。其实，只要能恰当地运用上述的任何一个句式，考生的作文就会出现闪光点，就会取得比较好的成绩。