Plants are more effi cient at acquiring carbon than are fung

[shaw.s.li]

Plants are more effi cient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

(A) Plants are more effi cient at acquiring carbon than are fungi,

(B) Plants are more effi cient at acquiring carbon than fungi,

(C) Plants are more effi cient than fungi at acquiring carbon,

(D) Plants, more effi cient than fungi at acquiring carbon,

(E) Plants acquire carbon more effi ciently than fungi,

OA ->C

I understand the answer, but just have a question regarding choice A.

Is the comparison "A is better than is B" always incorrect?

For example, I know you can say "A is better at golf than B is". Can you also say "A is better at golf than is B?"

[RonPurewal]

Plants are more effi cient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

(A) Plants are more effi cient at acquiring carbon than are fungi,

(B) Plants are more effi cient at acquiring carbon than fungi,

(C) Plants are more effi cient than fungi at acquiring carbon,

(D) Plants, more effi cient than fungi at acquiring carbon,

(E) Plants acquire carbon more effi ciently than fungi,

OA ->C

I understand the answer, but just have a question regarding choice A.

Is the comparison "A is better than is B" always incorrect?

For example, I know you can say "A is better at golf than B is". Can you also say "A is better at golf than is B?"

yes.

also, if B is followed by a decently long modifier, then you *must* use the latter of these.
for instance,
i know more about shakespeare than my brother does
i know more about shakespeare than does my brother
both correct

BUT
i know more about shakespeare than my brother, who has never studied british literature, does
--> this sentence is basically unreadable (you'll have to read it several times before you can make any sense of "does"), so it's unacceptable.
i know more about shakespeare than does my brother, who has never studied british literature
--> correct.

--

regarding (a), that choice is incorrect because it illogically implies that there are fungi in the form of carbon dioxide. (the modifier "in the form of carbon dioxide" must be placed as close as possible to "carbon".)

[abemartin87]

Plants are more efficient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

(A) Plants are more efficient at acquiring carbon than are fungi,

(B) Plants are more efficient at acquiring carbon than fungi,

(C) Plants are more efficient than fungi at acquiring carbon,

(D) Plants, more efficient than fungi at acquiring carbon,

(E) Plants acquire carbon more efficiently than fungi,


Hi,

I narrowed down the answer choices to (A), (B), and (C).

There were no ambiguity problems to require the helping verb "are", although it is not grammatically incorrect to include it.
Is it correct to say the (A), (B), and (C) are all grammatically correct and mean the same thing?

(A) Plants are more efficient at acquiring carbon than are fungi
or Plants are more efficient at acquiring carbon than fungi are (at acquiring carbon)

(B) Plants are more efficient at acquiring carbon than fungi (are at acquiring carbon)

and

(C) Plants are more efficient than fungi at acquiring carbon


Is it safe to say that the issue with (A) and (B) really lie with the following modifier ", in the form of carbon dioxide, " which tries to modify "carbon", and not the the construction of the comparison or the addition of the helping verb "are"?

[saptadeepc]

Plants are more efficient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

(A) Plants are more efficient at acquiring carbon than are fungi,

(B) Plants are more efficient at acquiring carbon than fungi,

(C) Plants are more efficient than fungi at acquiring carbon,

(D) Plants, more efficient than fungi at acquiring carbon,

(E) Plants acquire carbon more efficiently than fungi,

'B' is ambiguous
The two possible meanings are
1. Plants are more efficient than fungi at acquiring carbon.
2. Plants are more efficient at acquiring carbon than plants are at acquiring fungi.

'C' is better than 'A' in one more aspect other than the issue of misplaced modifier.

The intended meaning of the sentence is - plants are more efficient both in "acquiring carbon" and in "converting the carbon"

In choice 'C' this idea is presented in parallel

Plants are more efficient than fungi at
acquiring carbon, <modifier>
and ( sign of parallelism )
converting it.

Whereas if we read 'A'

Plants are more efficient
at acquiring carbon than are fungi, <modifier>
and converting the carbon ( we are not saying it is more efficient than fungi here ) !

[abemartin87]

saptadeepc thanks for the wonderful analysis! Wouldn't be surprised if you were a MGMAT tutor.

[abemartin87]

Plants are more efficient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.


I see now that there is an ambiguity problem with (B) that (A) corrects with the helping verb "are".

Would it be safe to adopt this rule:

" COMMA + Preposition" is always an appositive modifier that ALWAYS modifies the preceding noun?

X, on the box
X, in the box
X, around the box
etc...

I know appositives can modify the ENTIRE clauses or the PRECEDING noun based on meaning. So can I say safely that " COMMA + Preposition" ALWAYS modifies the preceding noun?

Thank you so much!

[RonPurewal]

I know appositives can modify the ENTIRE clauses or the PRECEDING noun based on meaning. So can I say safely that " COMMA + Preposition" ALWAYS modifies the preceding noun?

Thank you so much!

no; prepositional phrases are marvelously flexible. they just need to be positioned in a place where they are clear, unambiguous, and as close as possible to their intended referent.

People protested against slavery, in their homes and in the streets. --> this is a correct sentence in which this kind of modifier modifies an entire clause.

when it comes to problems like this, you don't even have to have precise rules for how the modifiers work. instead, just look at the modifier placement in each choice RELATIVE to the other choices, and go for the choice(s) in which the modifier is placed closest to what it's actually talking about.
in this problem, the modifier is definitely talking about carbon, so you don't need precise rules for how the modifier works. you just have to pick the modifier that is placed as close as possible to "carbon".

[thanghnvn]

1) Thank you Ron, Can I say:
- comma+ preposition phrase is flexible
- comma+ do-ed phrase modify the immediately preceding noun
- comma+ do-ing phrase modiy the preceding clause

2)another thing of comparision.
In comparision, it is prefered to keep the verb in the second half of the comparision even when there is no problem with clearity. I see some gmatprep question tests this point. for example

- I learn English better than he does
is prefered to
- I learn English better than he
Am I correct?

[RonPurewal]

1) Thank you Ron, Can I say:
- comma+ preposition phrase is flexible
- comma+ do-ed phrase modify the immediately preceding noun
- comma+ do-ing phrase modiy the preceding clause

thanghnvn, i'm noticing that you have posted this exact question on over 10 forum threads. please don't make redundant posts, or else we will have to start ignoring or deleting them. thanks.

2)another thing of comparision.
In comparision, it is prefered to keep the verb in the second half of the comparision even when there is no problem with clearity.

not true.

I see some gmatprep question tests this point.

please cite the problem you're talking about. it would be helpful to have the actual problem in front of us; otherwise, there's no guarantee that you are remembering things correctly.

- I learn English better than he does
is prefered to
- I learn English better than he
Am I correct?

no. if both are fine, then both are fine (and the one without the unnecessary verb is slightly better, although you won't be asked to choose between two things that are correct).

[rudransh]

In choice 'C' this idea is presented in parallel

Plants are more efficient than fungi at
acquiring carbon, <modifier>
and ( sign of parallelism )
converting it.

Whereas if we read 'A'

Plants are more efficient
at acquiring carbon than are fungi, <modifier>
and converting the carbon ( we are not saying it is more efficient than fungi here ) !

cool...thanks for this post, exactly what I was looking for.

Between A and C, C follows parallelism in addition to correct placement of modifier.

[jnelson0612]

Glad we could help! :-)

[ASangwan]

Hi Ron,

Just looking at the comparison in option A and B here(ignoring the modifier) its not really easy to make a rule for ambiguity while doing comparisons right?
I mean, you tried to make one in this post with the tycoon , Jones and anyone else:

salt-deposits-and-moisture-t5617.html

But its really not applicable here right?. Or can we say that there are three things in this question also, (plants, fungi & carbon) that make the comparison ambiguous without the verb (are)?

I'm just trying to make a set of rules for comparison and struggling to do so.

thanks.

[tim]

i'm not entirely sure why you need to make a rule. just look at the sentence and ask what is being compared. if it's possible that there are two or more grammatically viable interpretations, you have an incorrect answer choice. this is the case with B (are we comparing carbon to plants or to fungi?), but A clears up the problem by including the verb "are"..

[mcmebk]

I know appositives can modify the ENTIRE clauses or the PRECEDING noun based on meaning. So can I say safely that " COMMA + Preposition" ALWAYS modifies the preceding noun?

Thank you so much!

no; prepositional phrases are marvelously flexible. they just need to be positioned in a place where they are clear, unambiguous, and as close as possible to their intended referent.

People protested against slavery, in their homes and in the streets. --> this is a correct sentence in which this kind of modifier modifies an entire clause.

when it comes to problems like this, you don't even have to have precise rules for how the modifiers work. instead, just look at the modifier placement in each choice RELATIVE to the other choices, and go for the choice(s) in which the modifier is placed closest to what it's actually talking about.
in this problem, the modifier is definitely talking about carbon, so you don't need precise rules for how the modifier works. you just have to pick the modifier that is placed as close as possible to "carbon".

Hi Ron

In this question, I understand C is better than A, because the modifier is closer to the modified subject.

But you have mentioned in another post, that because prepositional phrase modifiers are flexible -- they may require the reader's common sense to resolve their meaning.

for instance, the following two examples are both correct:
i bought a belt with a removable buckle.
i bought a belt with my gift certificate.
in the first of these examples, "with a removable buckle" modifies the noun "belt". in the second example, "with my gift certificate" modifies the action of buying the belt.

In this question, because it is non-sense to think fungs is "in the form of carbon dioxide", neither plants, there is not really confusion which noun it should modify, right?

Another thing is, what is the difference between comma+prepositional phrase and NO COMMA + prepositional? I noticed there is a split between answer A and C, and would like to know if prepositional phrase functions differently in these two situations.

Thank you Ron.

[jlucero]

Let's flip your two examples to understand the difference in the two:

i bought a belt with a removable buckle.
i bought a belt with my gift certificate.

With a removable buckle I bought a belt. (not ok)
With my gift certificate, I bought a belt. (ok)

The difference is that with lots of nouns in a sentence, noun modifiers need to be as close to the noun that they are describing as possible. Fewer verbs mean greater flexibility in where their modifiers can be placed.

You say that it is non-sense to think that fungus is in the form of carbon dioxide, but that's only because you know what the meaning of the sentence should be. Choose the sentences and modifiers that couldn't possibly be understood any other way.

I'm not sure if your last paragraph is one or two questions, but I don't see a comma split b/w A&C, so I'm not sure what you're referencing and no answer choice on the GMAT comes down to proper comma usage. However, the placement of a prepositional phrase can be essential as it can make a huge difference in meaning:

X is more Y than Z. (B's construction = wrong meaning)

vs

X is more Y than Z is. (A's construction)
X is more than Z at doing Y. (C's construction)

While A & C have different structure, their meaning is similar.