if you use a single dash, then the stuff that is set off by the dash must actually continue all the way to the end of the sentence. if you are going to block off a modifier with dashes, then you must use two dashes to block off the modifier.

i.e., there is no such thing as a modifier that is blocked off by a dash on the left, but by a comma on the right. if you have a modifier that does not extend to the end of the sentence, then you must use either two dashes or two commas to set it off.
therefore, your question here ("if there is a dash followed by a comma") actually doesn't make sense, because in any such situation the dash and the comma would be entirely unrelated to each other.



in that context, i meant
COMMA + (modifier that continues until the end of the sentence)
is the same as
DASH + (modifier that continues until the end of the sentence)


incorrect analysis.
i posted the correct analysis of this sort of situation here:
post43518.html#p43518

I have a doubt here .. Can you refer to "compounds" as 'that'. In my knowledge 'that' is used for singular reference. Could anyone shed some light on this?

There is a tricky distinction here between two uses of that. When that is used as a relative pronoun (to introduce a noun-modifying clause) it can modify a singular or a plural verb. When that is used as what is called a 'demonstrative pronoun,' it must be singular.

Now, I don't want you to memorize the term 'demonstrative pronoun,' so here's an easy way to keep track: If that touches the noun or noun phrase it modifies, it can be singular or plural. If that refers to something it doesn't touch, it must be singular.

And don't forget that that is used in other ways to. In that sentence I just wrote it introduces a subordinate clause. And in the second sentence of this paragraph that is an adjective.

Why C is wrong ?

Let's compare C to the correct answer, D.

C. come from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C, and
D. come from antioxidants—compounds that are also found in beta carotene, vitamin E, and vitamin C and that

Since the word "and" is a parallel marker, we must check parallelism. Notice how D is parallel after the dash:
compounds that are . . . . and that inhibit
We have nice verb parallelism here.

C breaks this parallelism by joining a noun and a verb:
compounds . . . and inhibit

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Jamie Nelson
ManhattanGMAT Instructor

Most of the purported health benefits of tea come…. (plural) CORRECT

What happened if the sentence starts by…

The most of the purported health benefits of tea…. (singular)

Does the subject change? The subject will be “the most…” so the verb is singular. Right?

The most of the purported health benefits of tea comes

Thank you

there is no such construction in english.

perhaps you are thinking of "the most ADJ" -- as in this song is the most beautiful thing i've heard in months.
or perhaps you are thinking of the spanish noun la mayoría, which can't be translated in this way.

hi ron,

just wanted to know whether "they" can be used to refer objects like health benefits, compounds,etc. i was in a mindset that "they" can only be used to refer beings like humans,animals,people,etc

no, "they" can refer to any plural noun..

_________________
Tim Sanders
Manhattan GMAT Instructor