Air is to us what water is to fish. 我們離不開空氣，就像魚兒離不開水一樣。　　

Engines are to machines what hearts are to animals. 發動機對機器之關系猶如心臟對動物之關系。　　

　　Reading　　 is to the mind what food is to the body. 讀書與思想的關系就好比食物與健康的關系。　　

What blood vessel is to a man’s body, railway is to transportation. 鐵路對于運輸猶如血管對于人體一樣重要。　

What salt is to food, wit and humour are to conversation and literature. 雋語與幽默和會話與文學的關系就像鹽和食物的關系一樣。　

■《英漢多功能詞典》（外研社）和《英語常見問題解答大詞典》（黑龍江人民出版社）等則認為這類句型中的 what 為關系代詞。并舉例：　　

Engines are to machines what hearts are to animals. 發動機對機器之關系猶如心臟對動物之關系。　　

Railway is to transportation what blood is to a man's body. 鐵路對于交通的重要性，就如同血管對于身體的重要性一樣。　　

Manure is to crops what food is to man. 肥料對于農作物，就如同食物對人一樣。　　

Color, line, mass, space and texture are to a painter what words are to an author. 顏色、線條、主體、空間和結構對畫家而言就像詞匯對于作家一樣重要。