主语补足语
主语补足语即被动语态中的宾语补足语。
eg.They caught boy stealing.
被动语态 The boy was caught stealing.
stealing 即为主语补足语
被动语态后的主语补足语
对于主语补足语，语法家们各有不同的看法。有的把连系动词后面的部分称作主语补足语；有的又把被动语态后的补足语称作表语，与被动语态一起称作复合谓语。笔者通过教学体会到，还是把被动语态后面的补足语称作主语补足语好些。这是因为学生很容易接受“宾语补足语”，而如果把带有宾语补足语的句子变成被动句，原来补充说明宾语的部分就变成补充说明主语了。
一、被动语态的主语补足语与主动语态的宾语补足语是密切相关的。例如：
(1) I saw him playing basketball yesterday.
(2) He was seen playing basketball yesterday.
句（1）中的含义不是我看见他，而是我看见他正在打篮球。playing basketball是宾语him的补足语。所以叫宾语补足语。
句（2）中的含义也不是他被看，而是别人看见他正在打篮球。这里的playing basketball是主语he的补足语，故称作主语补足语。主语和主语补足语一起称作复合主语。所以含有主语补足语的句子一般是被动语态，谓语动词是可以接复合宾语（宾语+宾语补足语）的及物动词。句首的主语就是主语补足语的逻辑主语。
二、主语补足语形式种种
1. 动词elect, call, name, make, find, leave等后面常接名词用作主语补足语。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. 动词keep, make, paint, cut, burn, beat, wash, find, consider, wipe等后面常接形容词用作主语补足语。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. 动词see, watch, hear, feel, listen to, look at, imagine等后面接分词用作主语补足语。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.感官动词see, watch, hear, notice, feel, make等后面接带to的不定式用作主语补足语。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. 介词短语用作主语补足语。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后面接名词、形容词、分词等用作主语补足语。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引导的名词性从句用作主语补足语。例如：
The boy has been made what he is.
三、 主语补足语的判别
1.看句中的动词是不是可接复合宾语，而且是不是被动语态，与此同时还要看其后部分的逻辑主语是不是句子的主语。
2. 另一种最简单的方法是：如果还不能看出来就可以把全句改成主动语态，加上一个主语we或people等。改成主动语态后，看后面是不是变成了“宾语+宾语补足语”了，这样我们就可以判别原句后面是不是主语补足语。例如：
被动句：She was found reading in the library. (主语补足语)
主动句：We found her reading in the library. (宾语+宾语补足语)
被动语态
一、 被动语态的用法：
1. 一般现在时的被动语态构成：is / am / are + 及物动词的过去分词
Our classroom is cleaned everyday.
I am asked to study hard.
Knives are used for cutting things.
2. 一般过去时的被动语态构成：was / were + 及物动词的过去分词
A new shop was built last year.
Dinosaur eggs were laid long long ago.
3. 现在完成时的被动语态构成：has / have + been + 及物动词的过去分词
This book has been translated into many languages.
Many man-made satellites have been sent up into space by many countries.
4. 一般将来时的被动语态构成：will+ be + 及物动词的过去分词
A new hospital will be built in our city.
Many more trees will be planted next year.
5. 含有情态动词的被动语态构成：情态动词+ be + 及物动词的过去分词
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. 现在进行时的被动语态构成：am / is / are + being + 及物动词的过去分词
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. 不定式的被动语态：to + be + 及物动词的过去分词
There are two books to be read. →
There are twenty more trees to be planted.
二、 怎样把主动语态改成被动语态?
把主动语态改为被动语态非常简单，可以遵循以下几个步骤：
1. 先找出谓语动词；
2. 再找出谓语动词后的宾语；
3. 把宾语用作被动语态中的主语；
4. 注意人称、时态和数的变化。
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、 使用被动语态应注意的几个问题：
1. 不及物动词无被动语态。
What will happen in 100 years.
The dinosaurs disappeared about 65 million years ago.
2. 有些动词用主动形式表示被动意义。
This pen writes well.
This new book sells well.
3. 感官动词或使役动词使用省略to的动词不定式，主动语态中不带to ，但变为被动语态时，须加上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. 如果是接双宾语的动词改为被动语态时，直接宾语(物)作主语，那么动词后要用介词，这个介词是由与其搭配的动词决定。
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. 一些动词短语用于被动语态时，动词短语应当看作一个整体，而不能丢掉其中的介词或副词。
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.</CA>
补充：
系动词连接了主语和补语。这种结构中的补语是说明主语性状的，所以称为主语补足语。系动词作为实义动词的一类，具有本身的意义，但是在起到桥梁作用的同时，有些系动词会保持本身具有的意义，有些意义则会减弱或消失。例如：
1. I tasted the soup. ( taste 为及物动词，意思为“品尝”。)
2. The soup tastes wonderful. (taste 为系动词，意思为“尝起来，吃起来”，意思基本未变。)
3. He went to the cinema yesterday evening. ( go 是不及物动词，意思为“去，走”。)
4. At the news, he went mad. (go为系动词，失去了“go”的原义，意为“变得”。)
另外，英语中还有一定数量的不及物动词，完全保留了本身的词汇意义，同时又发挥着系动词的功能。它们与主语补足成分连用，所以这类词被称为“准系动词”(quasi-linking verb or half-linking verb)。用于“S+Vi+Cs”(S代表主语，Vi代表不及物动词，Cs代表主语补足语)这一句式的动词都属于这种用法。有时，主语补足语不紧跟系动词，有可能被其它状语成分隔开。以“go”为例：
5. At twenty-four, Tom went half-bald. ( go 为系动词，失去原义。)
6. After midnight, Tom went home bored.( go 为准系动词，保留原义，但同时又连接主语“Tom”和主补“bored”，“home”为副词，表示地点状语。)
用于这一句式的补语可以为各种形式，如名词词组(NP)，形容词词组(AP)，介词词组(Pr.P)，和分词短语(PP)等。现举例如下：
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.
类似的动词包括： 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.
类似的动词包括：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.
类似的动词包括：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.
类似的动词包括：arrive, die, fall, go, leave, lie, return, sit 等。