Hydrocarbons, with which fruit flies perfume themselves

[jlucero]

Ron, great explanation as always.
Just one question here.
Why is "those of" in choice D unnecessary.
"to distinguish their own species from those (species) of others (flies)" - sounds like "those of" is necessary and without "those of" we'd be comparing "species" with "others (flies)"
Another correct way that I could think of is: to distinguish their own species with others' (apostrophe)

I'm eager to understand the flaw in my thought (jotted down above) because I preferred D over E based on this thought only :( though I now know that the change in the meaning "that taste/to taste" could have been another criteria of evaluating choices but that didn't strike me specially because not all the times has this "original sentence (i.e. choice A)" worked for me.

Please help here

The proper comparison here is "their own species" to "other fly species." Flies ARE a species and don't HAVE a species.

Assisting flies in distinguishing their own species from those (the species) of others. WRONG

This would be saying flies are distinguishing their own species from the species of other "fly species".

A tricky point for sure, and a good reason why being able to eliminate (D) for other reasons is helpful when you may not remember 9th grade biology classification :)

[cumulonimbus]

Hydrocarbons, with which fruit flies perfume themselves in species-specific blends, are known to be important in courtship, and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of others.
A. and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of
B. and apparently this assists flies when they taste the hydrocarbons on prospective mates in distinguishing their own species from those of
C. which apparently assists flies that tastes the hydrocarbons on prospective mates in being able to distinguish their own species from
D. apparently assisting flies to taste the hydrocarbons on prospective mates to distinguish their own species from those of
E. apparently assisting flies that taste the hydrocarbons on prospective mates in distinguishing their own species from

A is wrong because "this " is ambiguous and also "from that of "
B is wrong "when"
C being
betwen D and E why D is wrong because if we say "their own species from those of others" so those refers to species or technically to whole "their own species " or there are other errors in D.
Please explain
This is GMAT Prep Question

Hi Ron,
I saw your explanation for this SC on one of your video's.
I understand that part after and is an explanation of the part before and.
My question is regarding
The choice A.
and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of
Doesn't TO here indicates that the part after AND is an explanation of part before and, or we only have to look for words like - thus, consequently or therefore.

[RonPurewal]

My question is regarding
The choice A.
and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of
Doesn't TO here indicates that the part after AND is an explanation of part before and, or we only have to look for words like - thus, consequently or therefore.

if the construction was just "flies do X to do Y", then "to do Y" would indicate a purpose/goal/etc.

that's not the construction that appears here, though. this sentence is written as "this assists flies ... to do Y".
first, "this" can't be used as a standalone pronoun. second, "assists X to do Y" is not idiomatic.

[samwong]

Hi Ron,

I'm a little confused about the use of comma -ING in this question. If a comma -ING is placed after the clause, it will modify that clause.

In the Aug 25, 2011 Thursday with Ron, you used the following sentence:

"My brother took extra classes every semester in college, graduating in three years."

I understand that "graduating" is the direct result of taking extra classes. You also said that the SUBJECT of the clause should be the source/agent/doer of the action described in the "-ING". In this case, "my brother" is the person "graduating in three years."

The main clause in this question is:

"Hydrocarbons are known to be important in courtship,"

In C, "courtship" assists the flies.
In E, "hydrocarbons are known" assists the flies.
I picked C because it made more sense. In E, how is the action "knowing hydrocarbons are important in courtship" assisting the flies? They seem to be unrelated to each other. For example, if I "know" that hydrocarbons are important in courtship, how is my knowledge going to assist the flies to distinguish their species from others?

Thanks Ron.

[RonPurewal]

In E, how is the action "knowing hydrocarbons are important in courtship" assisting the flies?

you've twisted the subject+action there.

the subject+action being modified is "Hydrocarbons ... are known to be important in courtship". that makes perfect sentence with the modifier, which gives a direct description of why/how the hydrocarbons are "known to be important".

the sentence makes no reference at all to who "knows" this.
in fact, that's the entire point of using the passive ("are known to be...") -- so that the sentence doesn't mention the identity of the people who know this fact (since that identity is completely unimportant here).

[RonPurewal]

*1.May I conclude that
the difference between structure 'X assists Y to do Z' and structure 'X assists Y in doing Z' is that the former structure implies that X actually does Z and that doing Z is the purpose of doing Y while the latter structure implies that Y, not X, actually does Z ?

Absolutely correct.

=================
*2. I remember that you have said that X does Y to accomplish Z means accomplishing Z is the purpose of doing Y.
Can this rule be applied to the structure ' X expect Y to do Z' ?
e.g. Analysts expect the company's dividend to grow by 30% this year.
I understand that it is the company's dividend (Y) not the analysts (X) that grow (do Z) by 30% this year.
How would you explain this, Ron?
When we meet a SC problem contains the structure ' X does Y to do Z ', how can we judge who does Z ?

It's a mix of two things:
* Familiarity with the constructions
* Common sense

In the case of "They expect the dividend to grow", the meaning is completely obvious. (The same should be true for any other use of this construction; "expecting Y" is not an action with a purpose, so that interpretation will be nonsense.)

So, at that point, it's an issue of whether you've seen the construction before. If you haven't seen it, then you should note it and remember it, preferably by making your own example(s) of it.

[RonPurewal]

Thank you for your patience and explanation in advance. Because I am not a native speaker, my question may be stupid. Please forgive me.

Enough already with things like "My question might be stupid" and "I feel guilty for posting so much".
I understand that these are intended as polite comments, but, in American professional culture, that's not the effect they have. Instead, these kinds of comments rarely serve to do anything other than annoy the listener. (It may be different in your culture; I don't know.)

This forum exists for questions like yours. You should not feel "guilty" or "stupid" about posting them. Just go ahead and post them.

(And, on top of all that, most of them are very good questions.)

[divineacclivity]

Ron could you please also explain what others is referring to ??

OWN species or just species ??
own would act as a qualifier here..right ?

Ron,

I still have doubts about "... in distinguishing their own species from others"

I'll take an example:
" ... in distinguishing his own house from that of his friend"
or
" ... in distinguishing his own house from his friend's"

we'd never say "... in distinguishing his own house from his friend". that sounds just wrong.

Does "from others" in option E refer to " from species of others" like in "others' (others apostrophe)"?

thanks in advance.

[RonPurewal]

In that sentence, "others" = other species.

I think you are confused because "others" can mean "other people", even if "people" doesn't appear in the sentence.
But "others" can also mean other X's, where X is some noun that's actually there.

[divineacclivity]

In that sentence, "others" = other species.

I think you are confused because "others" can mean "other people", even if "people" doesn't appear in the sentence.
But "others" can also mean other X's, where X is some noun that's actually there.

Thank you very much for your reply Ron.
Yes I thought "others" is only a plural of "other" meaning "other people/things".
I also used to think if I have to make it say X's (possessive form), i'd have to put an apostrophe as in: others'
e.g. others' blankets = blankets of others (/other people)

I even looked up the online dictionary and this word it used in its possessive form is as below:
we must respect others' rights.

Could you please tell me if this version of others (i.e. others meaning something of others or X's) is specific to gmat or is it a generally accepted usage otherwise as well?
Thank you very much in advance.

[RonPurewal]

This is not a possessive. It's their own species vs. other species.

As an analogy, My notes fell out onto the floor, so I can't distinguish my own book from others. (= my own book from other books)

If it were a possessive, it would need an apostrophe.
Sentences ending in apostrophes are just weird; if there was one, it would almost certainly be rephrased (e.g., those of others).

[divineacclivity]

This is not a possessive. It's their own species vs. other species.

As an analogy, My notes fell out onto the floor, so I can't distinguish my own book from others. (= my own book from other books)

If it were a possessive, it would need an apostrophe.
Sentences ending in apostrophes are just weird; if there was one, it would almost certainly be rephrased (e.g., those of others).

Ahhh, what a relief. I get it now. "others" here means "other species" not "others' species" or "species of others".

Thank you, thank you, thank you. Ron, your teaching skills are amazing.

[RonPurewal]

Thanks!

As always, I appreciate the kind words.

[divineacclivity]

Thanks!

As always, I appreciate the kind words.

You're being humble :)

[RonPurewal]

Nah. Relatively few people take the time to post such pleasantries; it's always nice when they do.