高三課本第十三單元有這樣兩句話：1)However，what happened later proved me wrong. 2)Franklin Blake，meanwhile，received a letter from Rosanna saying that she knew what he had done on the night the Moonstone disappeared.這兩句話都運用了what引導名詞性從句，如果我們平時常讀英語文章或常做英語試題，就不難發現what的使用無處不在。下面就歸納總結what引導名詞性從句的用法，希望對同學們有所幫助。
一.引導主語從句
1)What we need is more time.(what做need的賓語)
我們所需要的是更多的時間.
2)What really matters is that she wore a pair of white shoes.(what做matters的主語)
真正麻煩的是她穿了一雙白鞋.
二.引導賓語從句
1)People were perhaps more honest a long time ago when life was very different from what it is today.(what做從句中is的表語)
很久以前當生活與現在的生活完全不同時，人們或許更誠實.
2)People have heard what the President has said;they are waiting to see what he will do.(what分別做動詞heard和see的賓語)
人們已經聽到了總統所說的;他們正等著看總統會做什么.
三.引導表語從句
1)Whether ways will be found to stop pollution or not is just what worries the public.(what做從句中的主語)
是否能找到阻止污染的方法就是所令民眾擔心的事兒.
2)That is what I want to tell you.(what做從句中的賓語)
那就是我想告訴你的事兒.
3)The little girl is no longer what she used to be.(what做從句中的表語)
這個小女孩不再是過去的樣子了.
四.引導同位語從句
1)They have no idea at all what he is working on.(what做從句的賓語)
他們一點兒都不知道他正在做什么.
2)You have no idea what I suffered.(what做從句的賓語)
你不知道我所遭受的痛苦.
通過以上例句及解釋我們可以得出：what常用來引導名詞性從句，即主語從句，賓語從句，表語從句和同位語從句.what在引導名詞性從句時有兩個重要的特點：一是它在相應的名詞性從句中一定有含義，常表示“什么”，“所…的”，“…的樣子”等.二是它在相應的名詞性從句中一定做成分，而且常做主語，賓語或表語.
練習：
1.It is not yet pretty welu nderstood_____made the rainforest disappear year by year.
A.that B.when C.what D.how
2.The word media basicaly refers to_______we commonly call newspapers，magazines，radios and televisions.
A.which B.what C.why D.how
3.It’s well understood_____controls the flow of carbon dioxide in and out of theatmosphere today.
A.that B.what C.how D.whether
4.The small mountain village____we spent our holiday last month lies in_____is now part of Hubei.
A.which;where B.where;what C.that;which D.when;which
5.The reason why he was late was_____he had taken a wrong bus.
A.because B.whether C.what D.that
6.Why is Li Ming so late?I don’t know______.
A.can what the reason be B.what the reason can be C.the reason what can be D.what can the reason be
答案：C B B B D B
