Scientists have found signs that moving water changed

[eggpain24]

Scientists have found signs that moving water changed the chemical makeup of the surface of Mars in recent eras, therefore concluding that its crust is harboring up to three times as much water than was previously thought.

(A) eras, therefore concluding that its crust is harboring up to three times as much water than was
(B) eras, therefore concluding that the planet's crust harbors up to three times as much water or more as was
(C) eras and have therefore concluded that the planet's crust harbors up to three times as much water as
(D) eras and they have concluded, therefore, that its crust harbors up to three times as much water, or more, than
(E) eras and concluded, therefore, that the planet's crust is harboring up to three times more water as was

a question coming from Prep → the OA is "C"

I‘ve got a question about the split between“ comma+concluding” and “have concluded”

the former is adverbial modifier，and the second is independent verb connected by “and”

I’m wondering whether this split can be used or just a red-herring

as to the former one → adverbial modifier may imply the consequence of “Scientists have found signs that moving water changed the chemical makeup of the surface of Mars in recent”

as to the second one → despite the appearance of “and” indicates independence and sequential action of “verb”， the use of “therefore” also clearly demonstrates the relationship between “concluded” and “found”

therefore，is “comma+ving” vs. "therefore + main verb" an effective split here?

[bek007]

Splits can be misleading. Let's try to deal with the problem the other way.
A) Problem 1: pronoun "its" - where is the antecedent (water, chemical makeup, surface, Mars)? Certainly, water and crust would seem illogical, but who knows? :) If you look down the answer choices you will notice that "its" is replaced by word "the planet". A signal, is not it?

Problem 2: is with "as much than" construction. The correct idiom is "as much as".

Problem 3: finally and most problematically to me, is the meaning of the sentence. It sounds to me that "therefore concluding" modifies the discovery of scientists and suggests that conclusion was reached at the same time when the discovery happened. So, no gap between findings, analysis and conclusion. Though, I might be wrong.

B) Problems 2 and 3, I think

D) Problems 1 and 2. In addition, construction "Scientists have found ..... and THEY have concluded" is not OK.

E) Here, "and concluded" is OK as there is no need to repeat "have", I think. However, the usage of idiom "more as" is unacceptable ("more than" is the correct version).

I hope it explains the issue. To tell you the truth, split approach is useful only when you are 100% sure that the other way is incorrect (eg., less and few for uncountable and for countable, respectively).

[RonPurewal]

is “comma+ving” vs. "therefore + main verb" an effective split here?

Yes.

Comma + "concluding" is nonsense, because "...concluding" doesn't in any way describe the previous part.

The "conclusion" is something that the scientists did later.
• It's not a description of the previous part.
• Because this conclusion demanded active deduction on the scientists' part, it's not a necessary/inevitable consequence of the previous part. (Immediate and inevitable consequences can also be expressed with comma + __ing: e.g., The car ran up onto the sidewalk and into the crowd, injuring five pedestrians.)

So, yes, valid split.

And nicely done.

[thanghnvn]

"was "in A is correct or not? pls , explain

in other words, if I add "was" to choice C, is this correct?

[RonPurewal]

"was" is ok.
it's not necessary, though, because "previously" is there. so, the sentence is more efficient without it.

[thanghnvn]

"was" is ok.
it's not necessary, though, because "previously" is there. so, the sentence is more efficient without it.

thank you, Ron
I remember your 3 rules of ellipsis.
if the second half of comparison has a form of "to be", the first half must contain a form of "to be"
if the second half contain "do, did", the first half must contain action verb
if the second half contain helping verb, the first half must contain the same helping verb, which maybe is in different tense.

in the problem here. the first half has not a form of "to be", why can the second half contain a form of "to be".

pls, explain more. Thank you

[YuY283]

Hi Ron,

when "and" connects two present perfect verbs, can the second "have" be omitted? Scientist have found..and (have)therefore concluded...

Is that right?

Thanks for your explanation.

[RonPurewal]

Hi Ron,

when "and" connects two present perfect verbs, can the second "have" be omitted? Scientist have found..and (have)therefore concluded...

Is that right?

Thanks for your explanation.

the sentence can be written that way.
however, only a bad writer would omit the second 'have' when there's a sizable distance between the two verbs (as there is here). with this much distance between the verbs, any decent writer will include the second 'have' to re-orient the reader.
(try writing the sentence without the second 'have'. now, try to forget that you've already seen it, and read it from a new reader's point of view. you'll find that it is basically impossible to understand in one shot; you'll have to backpedal to figure out how the parallel structure works.)

if the two verbs are close enough together, the omission is no longer 'bad writing'.

[RonPurewal]

of course, nothing in the last post really matters for this exam, which will NEVER task you with stylistic ('good writing' / 'bad writing') decisions.
for the gmat exam, the only things that matter are...
...it's acceptable to write 'have' twice,
and
...it's also acceptable to omit the second 'have' (unless that omission creates a genuine ambiguity).

you will NEVER have to decide between the two versions, because a problem will never have two correct answers.

if you see this difference, IT'S THERE TO DISTRACT YOU.
ignore it.
go find some other criterion for elimination.

[YuY283]

of course, nothing in the last post really matters for this exam, which will NEVER task you with stylistic ('good writing' / 'bad writing') decisions.
for the gmat exam, the only things that matter are...
...it's acceptable to write 'have' twice,
and
...it's also acceptable to omit the second 'have' (unless that omission creates a genuine ambiguity).

you will NEVER have to decide between the two versions, because a problem will never have two correct answers.

if you see this difference, IT'S THERE TO DISTRACT YOU.
ignore it.
go find some other criterion for elimination.

I've got it! Thanks very much for your clear explanation:)

[RonPurewal]

no problem.

[rohit.manglik]

Hi Ron/Instructors,

We have "have found" and "have concluded". As I understood, have is used for an event that started in past and that is continuing right now. Scientists already found the signs or already concluded in the past. They are not finding those signs or concluding right now. What's wrong in this explanation?

I agree this construction is correct as it's an official question, just unable to understand it.

Thanks

[RonPurewal]

for an explanation, read this post, as well as the following ones:
https://www.manhattanprep.com/gmat/foru ... ml#p100119

have is used for an event that started in past and that is continuing right now.

^^ this is one possibility... if you have a verb for which it's actually a possibility. (see the link.)

for finding things this interpretation is impossible, because 'finding things' is something that happens at a single point.
it does not mean 'continuing', because, for this particular verb, 'continuing' is not possible.

[PrakharS433]

is “comma+ving” vs. "therefore + main verb" an effective split here?

Yes.

Comma + "concluding" is nonsense, because "...concluding" doesn't in any way describe the previous part.

The "conclusion" is something that the scientists did later.
• It's not a description of the previous part.
• Because this conclusion demanded active deduction on the scientists' part, it's not a necessary/inevitable consequence of the previous part. (Immediate and inevitable consequences can also be expressed with comma + __ing: e.g., The car ran up onto the sidewalk and into the crowd, injuring five pedestrians.)

So, yes, valid split.

And nicely done.

Hi Ron,

Can you please give some examples when can we use " Comma + Concluding" structure...???

Thanks

[aflaamM589]

"was" is ok.
it's not necessary, though, because "previously" is there. so, the sentence is more efficient without it.

Isn't was here case of blatant redundacy, two words describing same thing and therefore wrong straightaway(redundant)?

or just a preference, without was is bit better than with was

I approached it as a clear 3/2 split and crossed at the very instant without even looking at other errors in B and E.

Moreover, can you comment on thanghnvn's line of reasoning above for dropping was (to be verb) the second time because there is no to be verb in first part of the comparison

Thanks