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What is a general rule for use of auxiliary verbs in sentence? Should we duplicate it or not? For instance,

It is available for every item and (is) used with . . .

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    this is more about the coordinating conjunction "and". You can leave out both "it" and "is"
    – msam
    Commented Mar 13, 2014 at 10:59
  • As suggested in the above comment it is a question of how you structure the sentence. If you use and, you have to restate subject (it) and verb (is used).
    – user66974
    Commented Mar 13, 2014 at 14:11
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    @Josh61, no, you do not. You can leave them both out.
    – Janus Bahs Jacquet
    Commented Apr 12, 2014 at 17:41
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    See Conjunction Reduction.
    – John Lawler
    Commented Oct 21, 2019 at 20:57

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In this sentence, is is the main verb in the first part, and is the auxiliary verb in the second part. This makes deleting the second is ungrammatical. So you have two options:

It is available for every item and is used with …
It is available for every item and it is used with …

If is is the main verb in both parts, or the auxiliary verb in both parts, you can (optionally) delete its second use:

It is available for every item and ready to use with no complicated set-up.
It is packaged with every item and used with …

The same rule applies to has; don't delete the second usage if it plays two different grammatical roles (i.e., main verb and auxiliary verb):

*It has deadly venom and killed countless people. (Wrong)
It has deadly venom and has killed countless people. (Correct)

ADDED: From the comments, some people perceive that in the OP's sentence, used is a past participle that is close enough to an adjective that is can be deleted. I perceive deleting it as ungrammatical.

There are three possible uses for to be as a verb form: an auxiliary verb signalling the passive voice, an auxiliary verb signalling a continuous tense, and the main verb. I don't believe you can use ellipsis if the verb plays two of these different roles. Consider the following sentences, all of which I perceive as ungrammatical:

*He was incompetent and embezzling.
*He was incompetent and fired for that reason.
*He was embezzling and fired for that reason.

On the other hand, both the past participle and present participle can function as adjectives, and in this case you can use ellipsis to delete the verb. For example, I don't feel that there is anything wrong with the following sentence:

The child was tired, hungry, and crying.

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  • Could you provide a vetted grammar source for that? -- If you do, I'll up vote it. :)
    – F.E.
    Commented Apr 12, 2014 at 16:54
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    @F.E., having the sentence without the second has is grammatical, but as you note it changes the structure. The second clause ends up being in the past tense, not the perfect, and therefore does not temporally parallel the first clause.
    – Janus Bahs Jacquet
    Commented Apr 12, 2014 at 17:43
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    @Peter, I'm not sure I agree with you here. When is clearly has different functions, I agree that deletion is not usually possible (though I think it does occur even there); but I think used with in this case here is close enough to being a simple, true adjective (rather than part of a passive construction) that deletion works. At least, when I read it in my head, the version with deletion sounds as natural as the one without.
    – Janus Bahs Jacquet
    Commented Apr 12, 2014 at 17:47
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    @JanusBahsJacquet In your first example "He was fired and spent two years unemployed", the subject's semantic roles in the two coordinates are somewhat similar in that "he" doesn't have a dynamic agentive role in either; also, "was spent" isn't meaningful for the 2nd coordinate. In your 2nd example,the context set up by the fact that she was tenured sorta sets the reader up to interpret that "she" was the one doing the teaching. But in "The moose was sighted twice and killed the driver”, there's a drastic change in semantic roles in a very short interval--that's the problem, imo.
    – F.E.
    Commented Apr 12, 2014 at 19:11
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    Hmmm, still no vetted grammar source. Don't make me pull out my CGEL books (2002 and 1985). -- As to "There are three possible uses for to be as a verb form:", well I'm seeing at least six uses: copula be, progressive be, passive be, quasi-modal be, motional be, lexical be. (2002 CGEL, page 113)
    – F.E.
    Commented Apr 13, 2014 at 0:24

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