介词AS
1)She can't write like she used to. (informal)
2)She can't write as she used to.
“like”本来是个介词，但是，这里的“like”却引导了一个限定分句，从而起了连接词的作用。这种用“like”代替“as”的用法受到广泛批评，但在非正式文体中（尤其在美国英语里）是常见的。“like”在比较分句中的情况也是如此，如(?)He treats me like I was his sister.这里，许多人宁愿用“as if”或“as though”，因为人们普遍认为“like”用于这种功能是不符合标准的。形成鲜明对照的是，有时由于矫枉过正，甚至在作介词的“as”和“like”之间本来应该有效地体现出区别的场合，也用了“as”而不用“like”，如：
He spoke as a leader of mankind. ("in the capacity of")/like a leader of mankind ("in the manner of").
3)HZ always acts like she were older than Last Hermit. (informal)
4)HZ always acts as she were older than Last Hermit.
conj.
Usage Problem.
1. In the same way that; as: To dance like she does requires great discipline.
2. As if: It looks like we'll finish on time.
5)We regarded her as the best writer among us.
6)We regarded her the best writer among us.
7)They considered it as one of the landmark decisions of the civil rights movement.
8)They considered it one of the landmark decisions of the civil rights movement.
这里，“regard”后必须跟“as”，而“consider”后跟“as”却是多余的。类似的例子还有：
(i) 可有可无的“as”
appoint (as)
choose (as)
count (as)
esteem (as)
rate (as)
reckon (as)
report (as)
elect (as)
certify (as)
crown (as)
proclaim (as)
(ii)必不可少的“as”
accept as
acknowledge as
characterize as
class as
define as
describe as
intend as
see as
take as
treat as
use as
Usage Note: Traditionally, a distinction has been drawn between comparisons using as . . . as and comparisons using so . . . as. The so . . . as construction is traditionally required in negative
sentences (as in Shakespeare's "'tis not so deep as a well"), in questions (as in Is it so bad as she says?), and in certain if clauses (as in If it is so bad as you say, you ought to leave). But this so . . . as construction is becoming increasingly rare in American English, and the use of as . . . as is now entirely acceptable in all contexts. In a comparison involving both as . . . as and than, the second as should be retained in written style. One writes He is as smart as, or smarter than, his brother, not He is as smart or smarter than his brother, which is considered unacceptable in formal style. In many dialects, as is used in place of that in sentences like We are not sure as we want to go or It's not certain as he left. This construction is not sufficiently well established to be used in writing. As should be preceded by a comma when it expresses a causal relation, as in She won't be coming, as we didn't invite her. When used to express a time relation, as is not preceded by a comma: She was finishing the painting as I walked into the room. When a clause introduced by as begins a sentence, care should be taken that it is clear whether as is used to mean "because" or "at the same time as". The sentence As they were leaving, I walked to the door may mean either that I walked to the door because they left or at the same time that they were leaving. As is sometimes used superfluously to introduce the complements of verbs like consider, deem, and account, as in They considered it as one of the landmark decisions of the civil rights movement. The measure was deemed as unnecessary.
This usage may have arisen by analogy to regard and esteem, where as is standardly used in this way: We regarded her as the best writer among us. But the use of as with verbs like consider is not sufficiently well established to be acceptable in writing.
Regional Note: American dialects often vary from Standard English in the form and usage of relative pronouns. Where Standard English has three relative pronouns--who, which, and that--regional dialects, particularly those of the South and Midlands, allow as and what as relative pronouns: Them as thinks they can whup me jest come ahead. (Publication of the American Dialect Society). The car what hit him never stopped.
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Meunique