簡介
主動語態中的賓語補足語，可以轉化為被動語態中的主語補足語。
eg. They caught the boy stealing. （stealing 作為賓語補足語）
轉化為被動語態The boy was caught stealing. （stealing轉化為主語補足語）
關係
被動語態的主語補足語與主動語態的賓語補足語是密切相關的。例如：
(1) I saw him playing basketball yesterday.
(2) He was seen playing basketball yesterday.
句（1）中的含義不是我看見他，而是我看見他正在打籃球。playing basketball是賓語him的補足語。所以叫賓語補足語。
句（2）中的含義也不是他被看，而是別人看見他正在打籃球。這裡的playing basketball是主語he的補足語，故稱作主語補足語。主語和主語補足語一起稱作複合主語。所以含有主語補足語的句子一般是被動語態，謂語動詞是可以接複合賓語（賓語+賓語補足語）的及物動詞。句首的主語就是主語補足語的邏輯主語。
形式
1. 動詞elect, call, name, make, find, leave等後面常接名詞用作主語補足語。例如：
① The dog is called Karl.
② Coal is sometimes called stored-up sunlight.
③ He was found the right man for the job.
2. 動詞keep, make, paint, cut, burn, beat, wash, find, consider, wipe等後面常接形容詞用作主語補足語。例如：
① The door was painted white.
② The old man was found weak.
③ The classroom is always kept clean every day.
3. 動詞see, watch, hear, feel, listen to, look at, imagine等後面接分詞用作主語補足語。例如：
① He is often heard reading English.
② The professor was seen making an experiment in the chemistry lab.
③ The glass was found broken.
④ The classroom was found crowded with people.
4.感官動詞see, watch, hear, notice, feel, make等後面接帶to的不定式用作主語補足語。例如：
① He was seen to come upstairs.
② Ice is known to be in a solid state.
③ The spy was ordered to be hanged.
5.介詞短語用作主語補足語。例如：
① The books in the study must be kept in good order.
② He was found in good health.
③ English is considered of great importance for us.
6. as後面接名詞、形容詞、分詞等用作主語補足語。例如：
① English is taken as a useful means for research work.
② The news is considered as true.
③ The stool is usually thought as having four legs
④ The vase is thought as broken.
7. 由what引導的名詞性從句用作主語補足語。例如：
The boy has been made what he is.
判別方法
1.看句中的動詞是不是可接複合賓語，而且是不是被動語態，與此同時還要看其後部分的邏輯主語是不是句子的主語。
2. 另一種最簡單的方法是：如果還不能看出來就可以把全句改成主動語態，加上一個主語we或people等。改成主動語態後，看後面是不是變成了“賓語+賓語補足語”了，這樣我們就可以判別原句後面是不是主語補足語。例如：
被動句：She was found reading in the library. (主語補足語)
主動句：We found her reading in the library. (賓語+賓語補足語)
被動語態
一、被動語態的用法：
1.一般現在時的被動語態構成：is / am / are +及物動詞的過去分詞
Our classroom is cleaned everyday.
I am asked to study hard.
Knives are used for cutting things.
2.一般過去時的被動語態構成：was / were +及物動詞的過去分詞
A new shop was built last year.
Dinosaur eggs were laid long long ago.
3.現在完成時的被動語態構成：has / have + been +及物動詞的過去分詞
This book has been translated into many languages.
Many man-made satellites have been sent up into space by many countries.
4.一般將來時的被動語態構成：will+ be +及物動詞的過去分詞
A new hospital will be built in our city.
Many more trees will be planted next year.
5. 含有情態動詞的被動語態構成：情態動詞+ be +及物動詞的過去分詞
Young trees must be watered often.
Your mistakes should be corrected right now.
The door may be locked inside.
Your homework can be handed in tomorrow.
6.現在進行時的被動語態構成：am / is / are + being +及物動詞的過去分詞
Uncle Wang is mending my bike now.→
My bike is being repaired by Tom now.
They are planting trees over there. →
Trees are being planted over there by them.
7.不定式的被動語態：to + be +及物動詞的過去分詞
There are two books to be read.
There are twenty more trees to be planted.
二、 怎樣把主動語態改成被動語態?
把主動語態改為被動語態非常簡單，可以遵循以下幾個步驟：
1. 先找出謂語動詞；
2. 再找出謂語動詞後的賓語；
3. 把賓語用作被動語態中的主語；
4. 注意人稱、時態和數的變化。
例：1. Bruce writes a letter every week. →A letter is written by Bruce every week.
2. Li Lei mended the broken bike this morning.→The broken bike was mended by Li Lei this morning.
3. He has written two novels so far.→Two novels have been written by him so far.
4. They will plant ten trees tomorrow.→Ten trees will be planted by them tomorrow.
5. Lucy is writing a letter now.→A letter is being written by Lucy now.
6. You must lock the door when you leave.→The door must be locked when you leave.
三、 使用被動語態應注意的幾個問題：
1.不及物動詞無被動語態。
What will happen in 100 years.
The dinosaurs disappeared about 65 million years ago.
2. 有些動詞用主動形式表示被動意義。
This pen writes well.
This new book sells well.
3.感官動詞或使役動詞使用省略to的動詞不定式，主動語態中不帶to ，但變為被動語態時，須加上to 。
例：make somebody do something→somebody+ be +made to do something
see somebody do something→somebody +be +seen to do something
A girl saw my wallet drop when she passed by.→My wallet was seen to drop by a girl when she passed by.
The boss made the little boy do heavy work.→The little boy was made to do heavy work by the boss.
4. 如果是接雙賓語的動詞改為被動語態時，直接賓語(物)作主語，那么動詞後要用介詞，這個介詞是由與其搭配的動詞決定。
He gave me a book.→A book was given to me by him.
He showed me a ticket.→A ticket was shown to me by him.
My father bought me a new bike. →A new bike was bought for me by my father.
5. 一些動詞短語用於被動語態時，動詞短語應當看作一個整體，而不能丟掉其中的介詞或副詞。
We can’t laugh him. →He can’t be laugh by us.
He listens to the radio every day. →The radio is listened to by him every day.
The nurse is taking care of the sick man. →The sick man is being taken care of by the nurse.
補充說明
系動詞連線了主語和補語。這種結構中的補語是說明主語性狀的，所以稱為主語補足語。系動詞作為實義動詞的一類，具有本身的意義，但是在起到橋樑作用的同時，有些系動詞會保持本身具有的意義，有些意義則會減弱或消失。例如：
1. I tasted the soup. ( taste 為及物動詞，意思為“品嘗”。)
2. The soup tastes wonderful. (taste 為系動詞，意思為“嘗起來，吃起來”，意思基本未變。)
3. He went to the cinema yesterday evening. ( go 是不及物動詞，意思為“去，走”。)
4. At the news, he went mad. (go為系動詞，失去了“go”的原義，意為“變得”。)
另外，英語中還有一定數量的不及物動詞，完全保留了本身的辭彙意義，同時又發揮著系動詞的功能。它們與主語補足成分連用，所以這類詞被稱為“準系動詞”(quasi-linking verb or half-linking verb)。用於“S+Vi+Cs”(S代表主語，Vi代表不及物動詞，Cs代表主語補足語)這一句式的動詞都屬於這種用法。有時，主語補足語不緊跟系動詞，有可能被其它狀語成分隔開。以“go”為例：
5. At twenty-four, Tom went half-bald. ( go 為系動詞，失去原義。)
6. After midnight, Tom went home bored.( go 為準系動詞，保留原義，但同時又連線主語“Tom”和主補“bored”，“home”為副詞，表示地點狀語。)
用於這一句式的補語可以為各種形式，如名詞詞組(NP)，形容詞詞組(AP)，介詞詞組(Pr.P)，和分詞短語(PP)等。現舉例如下：
Type1: S + Vi +Cs (NP)
7. We parted the best friends.
= We were the best friends when we parted.
8. I stand before you today the representative of a family in grief.
= I am the representative of a family in grief when I stand before you today.
類似的動詞包括： come (back), die, fall, go, leave 等。
Type2: S + Vi +Cs (AP)
9. They were born poor, lived poor, and poor they died.
= They were poor when they were born; they were poor when they lived; they were poor when they died.
10. She married young.
= She was young when she married.
11. The morning dawned fresh and clear after the storm at night.
= When the morning dawned after the storm at night, it was fresh and clear.
類似的動詞包括：arrive, come (back), dawn, fall, leave, lie, marry, return, sit, stand, turn out 等。
Type3: S + Vi +Cs (Pr.P)
12. The parcel arrived in good condition.
= When the parcel arrived, it was in good condition.
13. They separated with feelings alienation.
= They had feelings alienation when they separated.
類似的動詞包括：come, die, fall, go, leave, lie, part, return, sit, stand等。
Type4: S + Vi +Cs (P.P)
14. They stood listening to him.
= They stood while they were listening to him.
15. He came home convinced that she was telling the truth.
= He came home and he was convinced that she was telling the truth.
類似的動詞包括：arrive, die, fall, go, leave, lie, return, sit 等。
