有一读者问： as for, as to 和 as far as...is concerned 有何区别？可否通用？
这三种说法有时是可以通用的，且看下面三个句子：
(1)As for me, I am not satisfied.
(2)As to me, I am not satisfied.
(3)As far as I am concerned , I am not satisfied.
这三个句子中的 as for, as to 和as far as...be concerned有几个共同点：1.皆意谓“就……而论”；2.皆是一种补充性声明，用以引起人们的注意；3.皆用作状语，位于句首。然而，上述三种说法并不完全等同，它们是各有其特点的。现将它们各自的特点分别作一探讨。
让我们先谈 as for。这是一短语介词，其后须接名词或代词。它有以下几个特点：
1. 它一般皆位于句首，意谓“就……而论，至于”，如上述句（1）。它很少位于句中，我们只见到过一例如下：
(4)He inquired as for my health.
2. 它常用来表示新的前文未提到过的事物（但也有用以表示前文已提到过的事物的情况），如：
(5)I know not what course others may take, but as for me, give me liberty, or give me death. （摘自美国政治家 Patrick Henry 1775年所作的演说）
(6)Much pasture land is under water; and as for the grain, most of that has been ruined. （as for 常与 and 连用）
3. 它较 as to 更加具有强调的意味，而且可有轻蔑、消极、不甚重要等含义，如：
(7)I've invited Andy, Bob and Mark. As for Stephen, I don't care if I never see him again in my life.
(8)The main dish was palatable, but as for the soup and the dessert...! （as for 常与 but 连用）
(9)That's the answer. As for the cause, how do I know?
(10)As for the rest of my infancy, there being nothing in it remarkable, I shall pass it over in silence.
4. as for 有时可省去，如：
(11)Myself, I wouldn't take any notice of her. （myself 之前省去了 as for）
5. 有些人说它的使用频率要高于 as to。
as to 也是一个短语介词，其后须接名词或代词，它有以下几特点：
1. 它不但可位于句首，如上述句（2），而且可以位于句中。位于句首时意谓“就……而论，至于”，常用以表示前文已提到过的或是已被料到的事物（但也有表示前文未提到过的事物的情况），如：
(12)As to that, I haven't decided yet.
(13)As to Smith, it is impossible to guess what line he will take.
(14)As to the journey, we must decide about that later.
(15)As to your suggestion that I fly out to see you, I don't think this would be a good idea.
2. as to 位于句中时，则意谓“关于”。它可置于名（代）词之后，动词之后以及形容词之后，如：
(16)I have no opinion as to the result. （置于名词之后。置于代词之后的情况见上述句（2））
(17)I doubted as to the last article of this eulogy. （置于动词之后）
(18)The worst thing you can do to an author is to be silent as to his works. （置于形容词之后）
3. 位于句中的 as to 除可后接单词外，还常后接间接疑问句，尤常后接 whether 引导的从句，如：
(19)As to whether he will consent, it is still too early to say.
(20)They disagree as to how he works.
(21)As to why they gave up the project, I'm still wondering.
(22)I have often wondered as to where the money had vanished.
(23)I could not help speculating as to who was going to fill the vacancy.
(24)When in doubt as to which answer is right, follow the text.
(25)As to what he is going to do, I did not ask him.
4. 有人认为同位语前的 as to 是多余的，尤其是 whether 引导的同位语之前的 as to，如：
(26)There is some question as to whether the bill will pass.
但是也有人对此有不同的看法。他们说即使英语学者的著作也不免有用此所谓“多余的” as to 的情况。他们还说，除打电报时不用“多余的” as to 之外，其它场合用不用，还是听凭于个人的好恶吧。
5. 有人认为位于句中的 as to 常被滥用，应被别的介词所替代，如常可被 about ，concerning 所替代。例如上述句（16）与（18）中的 as to 即可代之以 about ，再如下面一句中的 as to 可以代之以 concerning：
(27)The manufacturer complains that everything as to the future is left to the whim of the Board of Trade.
6. 注意位于句中的 as to 有时并不意谓“关于”，如：
(28)He so behaved as to impress company favorably. （as to 在此与 so 连用，表示目的）
(29)Transport rates vary both as to distance and as to weight. （as to 在此意谓“与……成比例”）
最后谈谈 as far as ... be concerned。 它也是一种用作句子状语的说法，其义是“就……而论”。 as far as 之后须接名词或代词，例除上述句（3）除外，再如：
(30)As far as the weather is concerned , I do not think it matters.
(31)As far as money is concerned , I'm in the hands of the bank manager.
这一说法的特点有：
1. 它不但可位于句首，亦可位于句中，如：
(32)It does not matter how clean we are as far as breathing is concerned .
2. 亦可说 so far as...be concerned ，其义与 as far as...be concerned 完全一样，如：
(33)I didn't enjoy the movie, and so far as that is concerned , I never like horror movies.
3. 第一个 as 在口语中可省去，如：
(34)Far as he's concerned , every man wearing a badge is a fascist, a crook, or a hustler. （far 前省去 as）
4. 由于 as (so)far as...be concerned 这一说法比较笨重，因而在当代英语中往往省去了 be concerned ，只剩下 as (so)far as ，如：
(35)As far as temperament , the Abyssinian cat is a most affectionate and loving companion.
(36)As far as raising kids, he didn't have a clue.
(37)So far as the program, it will be developed later.
但这种缩略形式到现在似乎仍停留在非正式英语中，在书面语中仍是不省去 be concerned 的好。
5. 注意 as far as...be concerned 中的 be 有时与其前的名（代）词的数并不一致，尤其在口语中，如：
(38)As far as Adams and Mr. Cohn is concerned ...（应为 are）
(39)As far as the infiltration of the armed services were concerned ...（应为 was ，但这里的 were 也可能是由于受到了其前的复数名词 services 的影响之故）
6. as far as...be concerned 还有两种变体：一种是 as far as...goes （went 等），实例如：
(40)His account is true as far as it goes .
另一种变体是 as far as concerns...，由于较为少见，这里就恕不举例了。
