as
1.such children as love their books里的as是关系代词，用作love的主语。such books as are loved by children里的as也是关系代词，用作are loved的主语。这样一讲，便知道such books as are loved by children里的are决不可省去，但这种verb to be很容易被忽略。例如：
- such points as are discussed in the book,
- such questions as are often asked by schoolboys,
- such preparations as are now being made,
- such arts as are practised by many
上述各种表达方式里as后面都必须有are。
2.下面各句里的as都是关系代词：
- The author was brought up in a small village, as is recounted in some of his stories.
- As is announced in today's papers, all the schools will reopen on 1 September.
- The boy was run over by a motor-car, as often happened in holidary season.
- As is often the case, the girl forgot to bring her dictionary.
- Helen was somewhat crazy, as all her acquaintances could see.
- As you will find out, all is now settled.
各句里的as都指主句所表达的意思，如第一句里的as指作家在小村里长大这件事。as的这种用法很普通，但也很容易被误认作连接词而加用it。例如：
The author was brought up in a small village, as it is recounted in some of his stories.
As it is announced in today's papers, all the schools will reopen on 1 September.
这it是要不得的。这样用法的关系代词as一定属于单数形式，as are和as were是不可能的。注意English as it is spoken in South England和China as I see her等表达方式里的as是连接词，不是关系代词，所以it和her不可少。
上面第一句和第二句里以as引导的从句都用属于被动语态的动词，那is可以省去，如The author was brought up in a small village, as recounted in some of his stories和As announced in today's papers, all the schools will reopen on 1 September。
3.2里所讲的as是关系代词，下面各句里的斜体as也是关系代词。
- Please come as soon as is possible. （is通常省去）
- He shows a readiness to work as hard as is necessary on any and every occasion.
- She always acts as appears best to her.
- We must assume that the accident occurred as is alleged. （is可以省去）
4.English as it is spoken in South England里的it is可以省去，成为English as spoken in South England，作“像英国南方所讲的那种英语”解，跟English spoken in South England（没有as）意思略有不同。又如the name as mentioned in the letter, the results as announced in today's paper和the answer as given below。
注意上述各种表达方式里的名词前面都没有such。假使有了such，便该在那过去分词前面加上verb to be，如such English as is spoken in South England和such a name as is mentioned in the letter。参见1
也得注意并非所有这类短语都可以在前面加上such，在后加上verb to be，如Truth as opposed to falsehood和actual conversation as distinguished from imagined conversation不可改作such truth as is opposed to falsehood和such actual conversation as is distinguished from imagined conversation。
跟as＋过去分词相仿的结构有grammar as against idiom, absolute as distinct from relative（绝对的，别于相对的）等。
本节里所举的as spoken，as mentioned，as announced，as given，as opposed和as distinguished跟2里所举的as recounted形式上相同，但语法上不同，这里各种表达方式等于as it is...或as they are...，但as recounted等于as is recounted。
5.下面各句都可以说，但用her和him比较普通些：
- I never knew so clever a girl as her.
I never knew so clever a girl as she. - I do not care to know such a man as him.
I do not care to know such a man as he.
当然，Such a man as he is welcome里的he不可改作him，I recognized the man as him who had called in the morning里的him不可改作he。
6.照一般语法书说，as...as...用在肯定句里，so...as...用在否定句里，如He is as old as she (is)和He is not so old as she (is)。但事实上并不都是这样。在否定句里用as...as...也普通，在口语里更普通。如He is not as old as she (is)。用了as...as...有时暗示着那第二个as后面的人或物有着高程度的那形容词（或副词）所指的性质，如He is not as old as she (is)有时含有“她是老年人”的意思。
在isn't，wasn't，don't，can't等后面，尤其多用as，如He isn't as old as she (is)比He isn't so old as she (is)普通，She doesn't work as quickly as her brother比She doesn't work so quickly as her brother普通。但假使在形容词或副词前面加了quite，却通常用so而不用as，如He isn't quite so old as she (is)比He isn't quite as old as she (is)普通。
not so old as she (is)不可能有“并非跟她同年（而比她年龄大）”的意思，not as old as she (is)才可能有，所以He is not as old as she (is), but much older里的as不可改作so。
7.He is as old as she当然不错，但在口语里往往说He is as old as her。
8.as可以表示原因。例如：As you are busy, you need not go with me. 这样用法的as语气比because轻。它所引导的从句通常在主句前面。要是把以as引导的从句用在主句后面，那从句里所说的事该是对方所知道的，否则句子便不好，如You need not go with me, as you are busy是好句子（因为对方当然知道他自己很忙），但I cannot go with you, as I am busy便不好（因为对方未必知道我很忙）。即使那从句里所说的事是对方所知道的，如果句子比较长，也最好不用在主句后面，如You need not go with me, as you are busy preparing your lessons and writing your exercises in various subjects里该把as从句用在主句前面。
As you are busy, you need not go with me可说相当于You are busy, so you need not go with me, As I am busy, I cannot go with you可说相当于I am busy, so I cannot go with you。注意用了as便不用so，用了so便不用as，不可两个单词都用。在两三百年以前这种两个单词都用的句子是普通的，但现在绝无仅有，不可仿效。As...so...现在并不作“因为…，所以…”解，却作“正像…，…”解。例如：As you like music, so I like poetry. 这句是“正像你喜欢音乐，我喜欢诗歌”，不是“因为你喜欢音乐，所以我喜欢诗歌”。
比较下面三句：
- In autocratic countries, as some are very rich, others are very poor.（在独裁统治的国家里，因为有些人很富，所以别人很穷。）
- In autocratic countries, some are very rich, so others are very poor.（意思同上句）
- In autocratic countries, as some are very rich, so others are very poor. （在独裁统治的国家里，正像有些人很富，别人很穷。）
9.As you are busy, you need not go with me不可改作Just as you are busy, you need not go with me。As you like music, so I like poetry可以改作Just as you like music, I like poetry。
10.beautiful as she is, late as he was, child as he is等表达方式里的as都作“虽然”解。注意那形容词或名词该用在as前面，也要注意那名词前面没有a。
这种结构里as前面不一定用形容词或名词，也有用副词或动词的。例如：
- Much as I should like to see you, I am afraid you may find it inconvenient to come in this hot weather.
- Search as they would, they could find nobody in the house.
但下面两句里的as并不作“虽然”解：
- Realizing as I do that I shall be very much occupied in the afternoon, I must send off all these letters this morning.
- Absorbed as he was in a mathematical problem, he did not notice my entering the room.
beautiful as she is当然是从属分句，主句的开首有时有yet。例如：Beautiful as she is, (yet) she is not a pleasant companion.
11.so...as和so...that不可混用，such...as和such...that也不可混用，注意下面各句：
- Here is so big a stone as no man can lift.
- Here is so big a stone that no man can lift it.
- Here is such a big stone as no man can lift.
- Here is such a big stone that no man can lift it.
用了as便不用it，用了that便用it。as是关系代词，that是连接词。也许有人要说：as也可以用作连接词，that也可以用作关系代词，那末不是it的用和不用没有关系了么？这道理也讲得通，可是习惯总是习惯，是不可改动的。
12.as用作“当…的时候”解的时候引导的从句里的动词不可作将来时态，如不可说Count the children as they will enter the room，该把will删去。比较下面两句：
Please post this letter for me as you pass the post-office. （当你经过邮局的时候，请替我寄这封信。）
Please post this letter for me as you will pass the post-office. （因为你将经过邮局，请替我寄这封信。）
13.8里说过as在表示原因的时候语气比because轻。Because it is getting late, we must start at once可以改作强势式It is because it is getting late that we must start at once。但As it is getting late, we must start at once不可改作It is as it is getting late that we must start at once。
14.so...as to...（不定式）跟...enough to...（不定式）相当，如Write so carefully as to make every sentence clear和Write carefully enough to make every sentence clear。注意不可用...enough as to...，如不可说Write carefully enough as to make every sentence clear，该把as删去。
15.as from主要用在法律、契约、公告等文件里，作“从…日开始”解。例如：The library will be open to the public as from 6 May, 2001. 和As from 6 May, 2001 the library has been open to the public. 在一般文字里不该用它。如不可说I shall use my bicycle as from Wednesday next，该把as删去。
16.The editor has bronght the material up to date as of May. 2001里的as of主要用在正式文件里。His air as of having forgotten about something important puzzled me里的as of作like that of解，现在比从前少用。
17.as per作“依照”解，是商业文件里的陈套语，如as per your request和as per our records。在一般文字里不该用它。该用according to。
18.He often talks to me as if（或as though，现在as if比as though普通得多）he were my father等于He often talks to me as he would talk if he were my father。were属于虚拟语气，不该改作is，下面两句都有错：
- The party goes on as if（或as though）nothing has happened.
- They are running about as if（或as though）they are madmen.
has该改作had，are该改作were。
但在It looks as if（或as though）和It seems as if（或as though）后面往往用属于现在时态的动词。例如：It looks（或seems）as if（或as though）a storm will soon come. 不过有些语法家以为这里总该把will改作would。He is running about as if（或as though）he were a madman和He is running about as if（或as though）he was a madman都可以说，不过有些语法家以为总该用were。
He ran about as if（或as though）he were a madman, He ran about as if（或as though）he was a madman和He ran about as if（或as though）he had been a madman都可以说，但用were不及用was普通，用had been很不普通。
19.as for和as to都可以用在句首，作“至于…”解。例如：As for（或As to）his father, I do not know him at all. 但as to可以用在句中，作“关于…”解，as for却不可，如I am in doubt as to his nationality和Nothing as to his past is known两句里的as to都不可改作as for。
as to这样用作“关于…”解很普通，有些英美人不赞成，说它意思模糊，但用得适当，意思并不模糊。不过该注意，在可能用确切些的介词的时候，最好不用as to，如下面各种表达方式里的介词不该改作as to：
- my plans for the future, a keen interest in science,
- a correct idea of love, his views on education,
- her objections to the scheme, their attitude towards us
20.as to往往是多余的，如下面各句里的as to该删去：
- I asked him as to what he wanted.
- I do not care as to when she will arrive there.
- Doubt is expressed as to whether they are safe or not.
- An interesting question remains as to where the rare plant is to be found.
21.as to不但往往被多余地使用，而且往往引起语法上的毛病。如An interesting question remains as to where the rare plant is to be found里的as to虽然是多余的，却不算错，但The question remains as to where it is to be found要算错了，因为the question该有一个indirect question做它的同位语。同样地，the doubt as to...也是错的。
It is not quite clear as to where the rare plant is to be found等句子里的as to用得更错，因为句首的It指where the rare plant is to be found这一从句，这从句属于主格，当然不可同时作as to的宾语。
还有用了as to很容易把它后面该用的to忘掉，如下面各句里斜体的to很容易被忘掉（实际是不可省的）：
- I want to find out as to whom these papers belong to.
- He advised me as to whom I should apply to for help.
- No information is obtainable as to to what extent things have improved.
22.as to里的to是介词，不是不定式的符号，so as to...和such as to...里的to是不定式的符号，不是介词，比较下面各句：
- As to writing English, he cannot do much.
- We must work hard so as to serve the people better.
- The problem is such as to interest only a few.
23.as for只可以用在句首，通常全句有轻视或消极的意思。例如：
- As for that young man, I am ashamed of him.
- As for the other books, nobody looks upon them as of much importance.
- As for a visit to the city, I am afraid it is out of the question at present.
通常不说：
- As for that young man, I am proud of him.
- As for the other books, everybody looks upon them as of great importance.
24.as best I（或you等）can和as well as I（或you等）can都作“竭力地”解，注意第一种表达方式里best后面没有as。
25.as it is，as it was和as it were三种表达方式不可混用。as it is和as it was都作“在事实上”或“就实际情形而论”解，第一种表达方式属于现在时态，第二种表达方式属于过去时态，如As it is, we cannot help her和As it was, we could not help her。As it were意思大不相同，作“好像”、“有几分相似”或“未尝不可说”解，were属于虚拟语气，可以用在任何时态的句子里。例如：He is（或was，或has always been）, as it were, friends with his dog.
26.(so far) as concerns，as follows和as regards（这里regards后面不可加上to）三种表达方式里的动词都有s，不可更改。
27.as well as跟and不同，也跟not only...but (also)...不同，A as well as B=not only B but also A，作“不独B，而且A”解。I am a Chinese, but I have foreign friends as well as Chinese friends是通的，I am a Chinese, but I have Chinese friends as well as foreign friends却讲不通。
28.A, B, as well as C是不该用的，如不该说I read French, German, as well as English。“我不仅读英语，而且读法语和德语”该说I read French and German as well as English。
29.as well as是连接词，不是介词，如不可说He advised me as well as answering my question，该把answering改作answered。He is a painter, engineer, and poet as well as being a sculptor里的being该删去。
30.both...as well as...是错误的，绝对不可用。
31.not only...but...as well颇有人用，但不及not only...but also...或not only...but...普通。
32.下面两句意思不同：
- I shall not go as well as you. （你将去，但我将不去。）
- I, as well as you, shall not go. （你将不去，我也将不去。）
33.as and when是公文里的陈套语，如As and when we get further particulars, we shall let you know。用when就够了。
