Eduard,
   When you say your native speaker students generate 70% ungrammatical
sentences, you are probably using the term in a rather unique way.
   "He worked for as long as he could" strikes me as perfectly
grammatical, as something I would easily say and easily understand. We
would need a corpus to include it, but we would need a corpus to
classify it as ungrammatical as well. >
   I gave one example where "for" helps clarify, and I'll try another. 
"He painted the lines [for] as long as he could."  Without the "for",
it's a statement about the length of the lines.  With the "for", it's a
statement about how long he would work. The "for" makes the notion of
duration clear.
If it showed up in my students' writing, I would never think of it as
ungrammatical.

Craig


 Hi!
>
> I like Stephen Seagal's movies and I often look for smart lines in
> them. In “Under Siege 2” one of the characters says: “Assumption is
> the mother of all…mistakes.”
>
> The lengthy grammatical analysis on this thread has been based on the
> assumption that the syntactic structure
>
> *He worked for as long as he could,
>
> is a grammatical sentence. We don’t know the origin of the sentence,
> and we don’t have its context. But what is the evidence that we are
> dealing with a grammatical sentence? “Native,” or “nonnative”
> speakers of English generate all the time ungrammatical sentences. In
> fact, as an instructor of English, I find out that my “native”
> students generate an average of 70% of  ungrammatical sentences in
> their essays.
>
> I believe that rewriting the sentence with the omission of “for”
> would make the analysis of the sentence much simpler. Why should we
> ignore "for"? Because we don't have any evidence (yet) that "for" has
> a high collocation frequency with "as long as." We would need to do
> some serious search in a few English language corpora in order to
> establish that the association "[for]+ as long as" is a frequent, and
> therefore natural, language collocation, and not an aberrant
> syntactic structure.
>
> So, let's rewrite the sentence with the omission of "for:"
>
> He worked as long as he could.
>
> All we have here now is a *complex sentence* with a main clause, “He
> worked,” and a subordinate clause, “He could (work),” linked by  a
> *complex adverbial subordinator of time* (See Celce-Murcia’s “The
> Grammar Book”).
>
> So, let me write again the sentence indicating its components:
>
> [He(Pronoun, Subject) worked (Verb, Simple Past, Predicate) –main
> clause] as long as (complex adverbial subordinator of time) [He
> (Pronoun, Subject) could (work – elided)/could work (Verb, Past
> Tense - Predicate) – subordinate clause].
>
> Simply, what we have here is a complex sentence composed of a main
> clause and a subordinate clause, and linked through a subordinator.
>
> Eduard
>
>
>
>
>
> On Mon, 27 Feb 2006, Edward Vavra wrote...
>
>>Having watched this thread developed, I'd like to note that Phil's
>>explanation is elegant. It is clear, and it does not require all the
>>grammatical apparatus that would make some of the other explanations
>>incomprehensible to most students.
>>Ed
>>
>>>>> [log in to unmask] 2/23/2006 3:16:33 PM >>>
>>
>>I think you need to take that phrase following "for" as an ellipsis
> for
>>"as long a time as he could" and the "for" as a standard
> preposition.
>>
>>This follows sentences like:
>>
>>    He worked for two hours
>>    he worked for two days
>>
>>    *He worked for as short as was necessary
>>    He worked for as short a time as was necessary
>>    *He worked for as intensely as necessary
>>
>>    He worked for as long as was necessary
>>    He worked for as long a time as was necessary
>>
>>    *He worked for as hard as he could
>>
>>The fact that this does not work with "short" or other adjectives
>>indicates it is exceptional in some way rather than systematic.
>>
>>Phil Bralich
>>
>>-----Original Message-----
>>>From: "Kathleen M. Ward" <[log in to unmask]>
>>>Sent: Feb 23, 2006 11:53 AM
>>>To: [log in to unmask]
>>>Subject: "work for" plus adverb clause
>>>
>>>One of my students asked me what to do with the following sentence:
>>>
>>>    He worked for as long as he could.
>>>
>>>Now, "as long as he could" is, I think pretty clearly an adverbial
>>>phrase, containing in itself a comparative clause with deletions.
> The
>>
>>>question is, what do you do with the "for"?  I understand that it
> can
>>
>>>be omitted--and then the analysis is easier.  But I would not want
> to
>>
>>>say that an adverbial phrase can be a complement/object of a
>>>preposition.  Is "for" a preposition here?  Is it a particle? Do I
>>just
>>>throw up my hands and call it an idiom?
>>>
>>>How do other people see this?
>>>
>>>Kathleen Ward
>>>UC Davis
>>>
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