<p>hi &1&2,</p>
<p>what seems to be throwing everybody is the lack of a main verb in the second half of the sentnece. the "are" you mentioned in your last post belongs before the word "usually." let me explain why.</p>
<p>to begin with, an "elliptical" sentence is one in which a portion of the sentence is omitted because it's understood to be there. this is often done for rhetorical effect. so i can write:</p>
<p>"My father is an architect; my mother is a writer."</p>
<p>in that sentence, everything necessary is included. both subjects ('my father' and 'my mother') have verbs ('is' and 'is') and objects ('an architect' and 'a writer,' respectively). you'll notice this sentence is an example of parallelism.</p>
<p>i could shorten that sentence to read this way:</p>
<p>"My father is an architect, my mother a writer."</p>
<p>in that instance, the verb "is," which was common to both of the parallel clauses in the first version of the sentence, has been removed from the second half of the sentence. i can do this because it's understood to be there, since it's common to both clauses.</p>
<p>this is the same thing we have going on in the CB sentence, and this is why the phrasing you mentioned actually DOES work:</p>
<p>"blah, blah, and blah are forms of dance, the dancers professionals."</p>
<p>we can only use this structure when the two clauses have parallel constructions. in the CB sentence, the constructions both work like this:</p>
<p>"[plural subject] are [plural object]."</p>
<p>if the "are" were placed before "performing," as you recommended, then the parallel structure would be destroyed. instead of being a main verb equating "dancers" with "highly trained professionals" in the second clause, the "are" would become a helping verb indicating the present tense of the verb "to perform." that would make the verb in the first clause "to be" and the verb in the second clause "to perform," which would mean the two clauses had nothing in common structurally, and which would make it impossible to omit the "are" in the second clause.</p>
<p>so to answer your other question, it's not the same structure as in</p>
<p>"ACT is better for me than SAT, science being my forte."</p>
<p>in fact, and not that it matters here, that structure isn't actually grammatically acceptable :) i know people talk like that all the time, but it's actually not an okay sentence. but i wouldn't worry about that for now.</p>
<p>also, i just want to point out one more time that you don't actually need to know about ellipsis to answer an SAT question. we know that every SAT ISE question has only one error in it at most, and we know that "is a form" can't possible be correct. that means we know that the rest of the sentence is error-free, even if we're not exactly sure why. so this particular test item isn't about ellipsis; it's about subject-verb agreement.</p>
<p>mike</p>