導語：表語從句（Predicative Clause）就是用一個句子作為表語。以下小編為大家介紹表語從句的定語文章，歡迎大家閱讀參考!
1．連繫動詞be,appear,seem,look等之後可以跟表語從句.
It was because he didn't pass the exam．那是因為他沒有通過考試.
It seems（that）he was late for the train．看來他沒搭上火車.
It appears that she was wrong．看來她錯了.
It seems to me that we should answer for this．在我看來,我們似乎應該對此事負責.
It appears to her that he wants to teach us all he has．在她看來,他似乎要把他所會的都教給我們.
2．引導表語從句的引導詞有以下幾類.
1）wh-疑問詞
My question is who left．我想問的是誰離開了.
What I wonder is when he left．我想知道他是何時離開的.
That's what he wants．那是他想要的.
This is where they once lived．這就是他們曾經住過的地方.
That is why he didn't come here．這就是他為何沒到這兒來的原因.
2）whether
My question is whether he left（or not）．我的問題是他是否離開了.
注：if不能引導表語從句.
3）that
The fact is that he left．事實是他離開了.
注：引導表語從句的連詞that間或可以省略.
The truth is（that）I didn't go there．事實是我沒去那兒.
4）because,as,as if,as though
It's just because he doesn't know her．這是僅僅因為他不認識她.
Things are not always as they seem to be．事物並不總是如其表象.
He looks as if he's tired．他好像累了.
定語從句:修飾一個名詞或代詞的從句稱為定語從句,一般緊跟在它所修飾的先行詞後面.2.關係詞:引導定語從句的關聯詞成為關係詞 關係詞有關係代詞和關係副詞.關係代詞有that,which,who,whom,whose,as
表語從句（Predicative Clause）就是用一個句子作為表語。說明主語是什麼，由名詞、形容詞或相當於名詞或形容詞的詞或短語充當表語。
表語是用來說明主語的身份、性質、品性、特徵和狀態的，表語常由名詞、形容詞、副詞、介詞短語、不定式、動詞的-ing、從句來充當，它常位於系動詞（be, become, appear, seem,look,sound,feel,get,smell等詞）之後。如果句子的表語也是由一個句子充當的，那麼這個充當表語的句子就叫做表語從句。
一、名詞作表語
Africa is a big continent.
非洲是個大洲。
That remains a puzzle to me.
這對我還是個難題。
二、代詞作表語
What’s your fax number?
你的傳真號是多少？
Who's your best friend?
你最好的朋友是誰？
三、形容詞作表語
I feel much better today.
我今天感覺好多了。
He is old but he is healthy。
他很老，但他很健康。
四、數詞作表語
She was the first to learn about it.
她是第一個知道的人。
五、不定式作表語
Her job is selling computers.
她的.工作是銷售電腦。
Our next step was to get raw materials ready.
我們下一步是把原料準備好。
作表語的不定式短語通常是說明主語的內容，這時主語通常是如下名詞：
hope, idea, job, plan, wish, aim, purpose, thing, business
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The purpose of new technologies is to make life easier, not to make it more difficult.
新技術的目的是使生活更便利，而不是更繁瑣。
Her wish is to become a singer.
她的願望是當一名歌手。
Our plan is to finish the work in two weeks.
我們的計劃就是在兩星期內完成這項工作。
六、介詞短語作表語
The patient is out of danger.
病人脫險了。
I don’t feel at ease.
我感到不自在。
七. 副詞作表語
The sun is up.
太陽升起來了。
I must be off now.
我得走了。
八.從句作表語
This is what he said.
這就是他所說的話。
表語從句的注意事項
A
表語從句一定要用正常語序。
False: The question is when can he arrive at the hotel.
Right: The question iswhen he can arrive at the hotel.
B
引導名詞性從句時if/whether（是否）用法辨析：
if不能引導表語從句，只能用whether 來引導。
引導賓語從句時if/whether可以互換，但介詞後面的賓語從句只能用whether來引導。
位於句首的主語從句只能用whether來引導，同位語從句也只能用whether來引導。
False: The question is if the enemy is marching towards us.
Right: The question is whether the enemy is marching towards us.
C
不像賓語從句，在有表語從句的複合句中，主句時態和從句時態可以不一致。
Right: The question is who will travel with me to Beijing tomorrow.
Right: The question is why he cried yesterday.
D
that在表語從句中不可以省掉。 表語從句只能置於主句之後，而主句的動詞只能是連繫動詞。
名詞性從句在be等系動詞後作表語時被稱為表語從句。
例如：
The problem is how we can get the things we need.
問題是我們怎樣能弄到我們需要的東西。（how 在表語從句中充當方式狀語）
The scissors are not what I need.
這把剪刀不是我所需要的。（what 在表語從句中充當賓語)
What I told him was that I would find him a good play.
我告訴他的是我會給他找個好劇本。（what在主語從句中作直接賓語， that作為表語從句的引導詞在該表語從句中不充當句子成分，但不能省略）
That is what I want to tell you.
那就是我想要對你講的。（what在表語從句中充當直接賓語)
That is why she failed to pass the exam.
那就是她考試不及格的原因。（why 在表語從句中充當原因狀語）
“That is why...”是常用句型， 意為“這就是……的原因/因此……”， 其中why引導的名詞性從句在句中作表語， 該句型通常用於針對前面已經說明過的原因進行總結，
又如：
That is why you see this old woman before you know,Jeanne.
珍妮， 這就是現在這個老太婆出現在你面前的原因。（前文提到Jeanne對老婦人顯得蒼老憔悴深感詫異，說話人對她講述了其中的原因之後，用這一句來進行概括）。
That is why I came.
這就是我來的原因。
下面是兩個與“That is why...”形式相似的結構， 它們與“That is why...”結構之間的關係要能夠辨析清楚：
(1）“That is why...”與“That is the reason why...”同義， 只不過從語法結構上講， “That is the reason why...”中why引導的是—個定語從句， 將其中的the reason去掉則與“That is why...”結構一樣， 例如：
That is (the reason) why I cannot agree.
這就是我不能同意的理由。
(2）“That is because...”句型中從屬連詞because引導的名詞性從句在此作表語， 這也是個常用句型， 意為“這就是為什麼……/因為……”。“That is because...”與“That is why...”之間的不同在於“That is because...”指原因或理由， “That is why...”則指由於各種原因所造成的後果， 例如：
He did not see the film last night. That is because he had to help his little sister with her homework.
昨天晚上他沒有去看電影， 那是因為他得幫助他的妹妹做作業。（第一句話說明結果， 第二句話說明原因）
He had seen the film before. That is why he did not see it last night.
他以前曾看過那部電影， 因此他昨天晚上沒有去看。（第一句話說明原因， 第二句話說明結果）
學識谷
