What表示比较关系的三种句型what一词用法很多，它可用作疑问代词，引导特殊疑问句；它可用作连接代词，引导名词性从句；它还可用于感叹句等。what作连接代词时还有一种特殊的用法，用来比较说明两种事物相同或相似的关系，起比喻作用，相当于连接词as，意为“正如”、“好比”、“就象一样”。现具体说明如下：1A is to B what C is to D1） Water is to fish what air is to man（水对鱼的关系就象空气对人的关系一样。）2）Ten is to five what eight is to four（10比5等于8比4）2What C is to D，A is to Bl）What food is to the body，a book is to the mind.（书籍对于心灵犹如食物对于身体。）2）What thegun is to a fighter，the pen is to a writer（作家的笔犹如战士的枪。）3What C is to D，that A is to B1）
