请看下面一题：

　　It is so difficult a problem that _________ student in this class _________ work it out.

　　A. any, can't B. no, can C. every, can D. no, can't

　　【分析】此题很容易误选A，因为从句意上看，选A可将此句理解为“这个问题是如此之难，这个班任何一个学生都不可能做出来”。但按英语习惯，any(任何一个)作为非肯定句，它只能出现在否定词 not 之后，而不能在其前，即可说 not any, 但不说 any not。所以正确答案应选B。又如：

　　这工作太难了，恐怕谁也干不了。

　　正：The work is too difficult. I'm afraid no one can do it.

　　误：The work is too difficult. I'm afraid any one can't do it.

　　什么也阻碍不了我同她结婚。

　　正：Nothing can prevent me from marrying her.

　　误：Anything can't prevent me from marrying her.

　　类似地，either (两者中的任意一个)作为非肯定词，它也应出现在否定词之后，而不能出现在否定词之前。如：

　　这两兄弟都不聪明。

　　正：Neither of the brothers is clever.

　　误：Either of the brothers is not clever.