1. They were all excited and happy.all是同位语，有修饰作用吗？

解答：all 是主语they的同位语

如果改成：He was all excited and happy.这个all是副词吗？

解答：all 为副词，相当于very,还可以与the+比较级和the+最高级结构连用表示强调,以及介词短语

He was all excited.=He was very excited.   

他非常兴奋。

Opening the windows made it all the hotter.  

打开窗户反而更热。

That was all the taller he grew.  

他顶多就长这么高。

Failure is the mother of success; you will be all the better for your failure.  

失败是成功之母; 你虽然失败了,反而会因此渐入佳境。

He was dressed all in black.   
他全身穿着黑衣服。

all除了以上修饰形容词，the+比较级和the+最高级结构连用表示强调,以及介词短语之外，还可以直接修饰名词特殊用法

all后面直接加名词的特殊用法:all+名词归纳如下：

(1)“be + all + noun (s)”结构的主语是人。

A:all 修饰抽象名词，多表示人们生活中的各种情绪和，all的意思是“很”、“非常”、充满……的”。

 Lanny was all tenderness and kindness. = Lanny was very tender and kind. 

兰尼十分温存和和蔼。

The little boy is all attention=The little boy is very attentive.

He is all life.= He is full of life.=He is very vigorous

他充满活力。

I am all astonishment.我非常惊恐。

He is all talk and no deed. 他只说不做。

Dodge was all cordiality. 道奇十分诚恳。

At the moment he was all energy. 那时，他劲头十足

B:all修饰复数名词，这些名词常常是人体的某一器官与之有关的动作。

When John told about the circus, the boys were all ears.

当约翰谈到马戏表演时，男孩们都仔细地倾听着。

He was all eyes as the train sped through the country. 

当火车飞速驰过村子的时候，他目不转睛地看着。

She was all smiles when she came in. 她进来时满脸笑容。

She was all tears. 她泪汪汪的。

(2)“be + all +noun”结构的主语是物。All所修饰的词多是表示不太令人高兴的、不太愉快的事。

That afternoon it seemed all disappointment. 那天下午好像很令人失望。

His talk was all rot. 他的谈话全是胡扯。

It’s all moonshine. 这全是空想。

That is all Greek to me. 那我可一窍不通。

The courtyard was all noise and bustle. 

院子里吵吵闹闹、乱哄哄的。

备注：all修饰名词这类短语还间或用用状语。

The Countess, all smiles, dame down to meet them. 

(伯爵夫人满面笑容地下来迎接他们。)

2.If that is the  case ,all the better .better是名词吗？

解答：（用于all the more, all the better等结构中）更加，愈加;这样更好；那更好

The living room is decorated in pale colours that make it all the more airy.  

起居室装饰成淡雅的颜色，显得更加宽敞明亮。

'How are you?' —'All the better for seeing you.'  

“你好吗？”—“好，看见你更好了。

Failure is the mother of success; you will be all the better for your failure.   
失败是成功之母; 你虽然失败了,反而会因此渐入佳境。

3.all能引导从句吗？

解答：all是代词，不是连词，因此不能引导从句，

（备注1：all +(the/指示代词/物主代词+名词=the/指示代词/物主代词+whole+名词,且名词不可以是可数名词复数或者不可数名词单数。）

That is all my life.=That is my whole life.

all the afternoon=the whole afternoon

all the world=the whole world

(备注2：如果名词是复数，或者不可数名词，则需要使用;all +(the/指示代词/物主代词+名词=the whole of +the/指示代词/物主代词+名词）

all the ink=the whole of the ink

all milk=the whole of milk

all Shanghai =the whole of Shanghai

all China=the whole of China

all his books=the whole of his books

all the apples=the whole of the apples

(备注3：all与代词连用时，需要使用代词+all或者all +of+代词 结构）

They all like me=All of them like me.

(备注4：all +of+名词，其名词前必须有限定词the/物主代词/指示代词 结构）

All of the books are mine.

All of the books belongs to me.

All the books belong to me.

(介词of可以省略，介词of后面为复数宾格代词them/us，则不能省略介词of）

All of us/them are from China.(介词of不能省略）

(备注5：all不可以与代词what同时使用）

That is all that he said.

=That is what he said.

(备注6：all 充当先行词时，由关系代词 that 引导定语从句）

All that glitters is not gold.

(备注7：all与否定副词not使用表示部分否定,要表示全部否定需要用none）

All my friends can't swim.（部分否定）

None of my friends can swim.(全部否定）

(备注8：all放在行为动词前，放在系动词，助动词之后，如果are 是最后一个单词，则放在系动词前）

The boy all study hard.

They are all doctors.

They have all gone there.

-Are you students?

-Yes, We all are.

4.all能指代上下文吗？

解答:all作为代词，可以指代全面提到所有内容

5.all是代词作同位语时，有修饰名词的作用吗？They are all students,all作同位语吗，有修饰作用吗，we are all wrong.这个all是副词，还是同位语？

解答：They are all students .=All of them are students .all是主语they的同位语：

We are all wrong=All of us are wrong .all属于同位语用法