在高中英语中，what是个极有用而又不容易被掌握的一个词，它除了做疑问词外，还有一些其他用法。下面就what的用法作一归纳：
　　一、用做疑问代词或疑问形容词，引导特殊疑问句，这是what的最基本用法例如：
　　What is your mother? (疑问代词)。What color is your favorite? （疑问形容词）。
　　注意此时它与疑问词which的区别：what表示泛指，意思是“什么”；而which具有选择性并规定有范围，意思是“哪个人或物”。如：Which book is yours, this one or that one?
　　二、用做关系代词，引导名词性从句，既可指代人（相当于the person/persons that），意思是“所…的人”，也可指代物（=all that, the thing/things that），表示“所…的事物。例如：
　　What we need is more money. （引导主语从句）
　　=All that we need is more money.
　　What moved us most were the hero’s deeds. （引导主语从句）
　　=The things that moved us most were the hero’s deeds.
　　He is not what he was a few years ago. （引导表语从句）
　　=He is not the person that he was a few years ago.
　　Show me what you have written. （引导宾语从句）
　　=Show me the things that you have written.
　　注意：1、What引导主语从句时，主句谓语动词的单复数形式取决于what所指代内容的单复数。2、What引导宾语从句时，其结構相当于一个名词短语。
　　三、What用于结构“What is the+抽象名词？”，what意思为“多少”。例如：
　　What’s the population of China? =How many people are there in China?
　　What’s your sister’s age? =How old is your sister?
　　四、what用做语气词，表示感叹，意为“多么”、“何等”。例如：
　　What happy children! =How happy the children are!
　　What an interesting film it is! =How interesting the film is!
　　五、What用做连词，含义和作用类似 as much as, the degree that等。例如：
　　The number of the students in our school is five times what it was ten years ago.
　　六、What和ever组成合成连词whatever，表示“无论。。。”“不管。。。”，相当于 no matter what…例如：Whatever you want to do, do it well.
　　=No matter what you want to do, do it well.
　　Take whatever you want.
　　注：在口语中，whatever可替代what，但语气较强烈，意为“究竟”、“到底”（=what on earth）。