2005年山东英语高考试题中有如下一道试题：
26． The shopkeeper did not want to sell for _______ he thought was not enough.
A. where B. how
C. what D. which
此题考查了what引导的宾语从句的用法，what在从句中作主语。
所以正确答案为C。what的用法是近几年高考的热点和难点。常见用法如下：
一、 what用作关系代词，也即连接代词，引导名词性从句, 可以作主语、宾语、定语
1. 引导主语从句
例1 What made the school proud was that more than 90％ of the students had been admitted to key universities. 使学校骄傲的是90％的学生被重点大学录取。
例2 What makes the matter worse is that it begins to rain. 更糟糕的是开始下起雨来了。
2. 引导表语从句
例3 ---Are you still thinking about yesterday’s game ?
例4 The city is not what it used to be. 这个城市不再是先前的模样了。
3. 引导宾语从句
例5 A man’s worth lays not so much in what he has as in what he is. 人的价值不在于他有什么，而在于他是怎样的人。
例6 After what seemed like hours he came out with a bitter smile. 好像过了几个小时以后，他面带苦笑走了出来。
二、 what 用作关系形容词，作定语。意为“所…… 的全部,任何的”；与little、few 连用时，其含义多为“虽然少，但把所有的都…… ”
例7 The home improvements have taken what little there is of my spare time. 家庭环境的改善占去了我仅有的一点业余时间。
例8 Don’t worry. I will give you what help I can. 别担心，我一定尽我所能帮你。
例9 I will lend you what few reference books I can spare. 我愿把我用不着的虽然为数不多的参考书全部借给你。
三、 what惯用句式：A is to B what C is to D （比喻结构）A对B之关系犹如C对D之关系
例10 Air is to us what water is to fish. 空气对于我们犹如水对于鱼。
例11 What salt is to the food, wit and humour are to conversation and literature. 隽语与幽默之于会话与文学，恰象盐之于食物一样。
四、 what引导插入语,意为“还有的是，加之”
例12 He is handsome, and what is more, very rich. 他长得很英俊，而且还很富有。
例13 He is, what is called , a living dictionary. 他就是所谓的活词典。