導語：引導非限制性定語從句的單詞有幾個，下面小編講解由what引導的非限定性定語從句，歡迎參考。
引導從句的what：
what的基本意思是“什麼”，與用作疑問詞時所表示的意思相同，這個用法大家可能比較熟悉。如：
I don’t know what he wants. 我不知道他想要什麼。
Tell me what you need. 告訴我你需要什麼。
what的另一個意思是“……所……的一切東西”。比較：
I didn’t know what he wanted. 我不知道他想要什麼。
I gave her what she wanted. 我給了她想要的一切。
第一句中的 what 表示“什麼”，帶有疑問的意味；第二句中的 what 表示“所…的一切事或東西”，其用法相當於“名詞（用作關係代詞）+關係代詞”。下面就what的後一種用法再舉兩個例子：
What you say is quite true. 你說的完全是事實。
what you say引導的是主語從句，意思是“你所說的情況”，相當於everything that you say，其中的`everything為先行詞，that you say為修飾它的定語從句。
He saves what he earns. 他賺多少，積蓄多少。
句中的what he ears引導的是賓語從句，用作動詞save的賓語，意思是“他所賺的錢”，相當於all that he earns，其中all為先行詞，he earns為修飾它的定語從句。
首先請看下列例句：
1. Later they discovered, what was news to him, that Pamela was the headmaster’s daughter.
2. She is bright, and what is better,amiable.
3. She wore,what was common at that time,a red shirt.
從以上例句可以看出，這裡的what似乎起了一種指代作用，這些句子完全可以改為下面的句子：
a. Later they discovered that Pamela was the headmaster's daughter, which was news to him.
b. She is bright and amiable, which is better. （與原句意義不符合）
c. She wore a red shirt, which was common at that time.
由以上的轉換我們基本上可以得出不完全的結論，即，what可以引導插入語，一般情況下，what可以轉換為一個由which引導的非限定性定語從句。再如下面的例句：
4. Jackie made us all annoyed, what was worse, he ruined all our plan.
5. He never joined in the usual sports of the boys, and what is remarkable, never went out in a boat on the river.
6. He is an interesting speaker, and, what is more important, he knows his subject thoroughly.
由以上例句，我們還可以看出，what在引導此類插入語時，其謂語動詞常為連繫動詞。如：
7. I lost the chance, what seemed worse, nobody would employ me.
另外對於what一詞，補充如下片語和短語，請大家以饗：
1. and what not 等等。如：I bought sugar, tea, eggs and what not.
2. give what for 斥責、懲罰。如：I'll give you what for if you don't stop that noise!
3. guess what 告訴你一個訊息。Guess what! The boss is getting married.
4. I'll tell you what 我有一個主意。如：I'll tell you what--I'll be leaving for London soon.
5. know what is what 瞭解情況，在行。如：He's a clever fellow; he knows what's what.
6. know what one's about 有頭腦；會處理困境。如：It's a dangerous job, but I know what it's about.
7. or what 還是怎麼的。如：Shall we go or what?
8. so what 那又怎麼樣。如：You see he'll fire me. So what?
9. what for 做什麼用。如：What are you running for? What's this switch for?
10. what have you 等等這類東西；應有盡有。如：The store sells big ones, small ones, medium ones, or what have you.
11. what if 要是...怎麼辦。如：What if she finds out that you've lost her book?
12. what is what 基本情況。如：When it comes to cooking, Jenny knows what's what?
13. what of... 怎麼樣？如：So much for the Westbrooks. What of Shelley? Shelley gave his...
14. What of it? 那又有什麼關係呢？如：--This is the fourth time she's rung you in a week.--Well, what of it?
15. what the devil/hell... 他媽的...什麼/怎麼（表示氣憤。如：What the devil shall we do now?）
16. what with 由於...種種原因（多指不快之事）。如：What with the noise and the dogs we could hardly sleep late on Sunday.
