Scientists have found signs that moving water changed the chemical

Explain for me the "as well as previously thought" I don't get this.

Does this question pertain to this problem?

the correct idiom is AS ... AS (do not miss 2nd one)
if there is COMPARATIVE form, there comes THAN

+1 C

Parallelism.
Idioms: "more" requires "than", otherwise it is wrong.

It makes me wonder if the GMAT keep the sentences correctly punctuated. I did not eliminate using idioms. Haha! I just saw that therefore should follow semicolon... and leaves me with C and D... But D has two stand alone clause not separated by a comma and AND...

So I got C. Hmmm... Wonder if that was pure coincidence

It may sound rude but does it take too much to underline the incorrect part? to me a senetence with out underline looks like a gibrish all over

A) Lack of parallelism
Scientists have found signs......eras, therefore concluding that .....
B) Out for same reason.
C) Seems good..keep it on hold.
D) Wrong: as much water, or more, than
E) Wrong: times more water as was

So it is C.

A , B are wrong because we have IC connected to another IC by a comma .

the idiom is as much as or more than
In D 'as much , more than' is incorrect
In E 'more as' is incorrect

That keeps us with C which is the correct answer

Here is the notes that I got from Thrursday's with Ron session on March, 26 2015 The use of AND

See the video from 31:40 to 48:00 below


Analysis:
- 2 Actions: The scientists ..
Action (1) ... found evidence
Action (2) ... concluded XXXXX
Separate, or Two aspects of the same action
Here the actions are ..
found evidence .. (evaluated it for some time) .. then concluded it ..
So, Action (2) is not instantaneous with Action (1)

- Option (A),(B) usage of ", __ing" is WRONG !!!

Example: Scientists have found signs that moving water existed on Mars in the planet's recent history, disproving the idea that Mars has always been dry.
Here "found signs" and ", disproving" are instantaneous actions. So usage of ",__ing" is correct here.

- Option (D) usage of ".. three time as much, or more, than ... " (need to use "AS MUCH AS" not "AS MUCH THAN")

- Option (E) usage of ".. is harboring .." means this is happeneing right now.. not what we mean.

Answer (C)

Scientists (parallel elements)
- have found
- concluding

(A) eras, therefore concluding that its crust is harboring up to three times as much water than was
- continuous tense is unnecessary. As X as construct missing. “Was” is redundant as “thought” is in past tense already
(B) eras, therefore concluding that the planet's crust harbors up to three times as much water or more as was
- continuous tense is unnecessary. “Was” is redundant as “thought” is in past tense already
(C) eras and have therefore concluded that the planet's crust harbors up to three times as much water as
- correct
(D) eras and they have concluded, therefore, that its crust harbors up to three times as much water, or more, than
– "as a result of missing" with "therefore" as a modifier. More X than Y construct missing and As X as construct not correct.
(E) eras and concluded, therefore, that the planet's crust is harboring up to three times more water as was
– as a result of missing with therefore as a modifier. More X than Y construct missing. Continuous tense is unnecessary. “Was” is redundant as “thought” is in past tense already


Thanks

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

D is wrong because of AS MUCH AS. But is the construction eras and they have correct? 2 independent clause so there must be a COMMA before AND.
Is it correct?
What about placement of therefore in C, D, & E ?

daagh Sir,

Apart from the as...as and more.... than split,I have a question on this perticular problem.Is "concluding" wrong because it is not an instantaneous action?

techie

How did you deduce that concluding was not instant and must have happened long after? For all that, the scientists may have concluded the same moment they saw the evidence

Answer B.

I had previously marked C. I had completely missed the application of "more than" concept here .
"3 times as much as.. or more than " is correct.

Besides, I also thought that the "concluding" is a result of finding signs. So i went with C. But now I see that B is a better choice because of IDIOM error.

Hi Expert
In OA (option C)
there is a comparison between Water now Vs Water that was previously thought.
so if we see the construction without ellipsis .we will see this
the planet's crust harbors up to three times as much water as water that was previously thought.
Since in this sentence we have shift of tense from present to past , we have to keep verb in second part of comparison (during ellipses ) to convey proper tense of second part , otherwise the second part will conform the present tense of first part .
As per my understanding the proper sentence after ellipses would be look like this

.....the planet's crust harbors up to three times as much water as was previously thought.

Since i know the OA is absolutely correct . Please let me know where my reasoning is flawed?

Edit: it was a typo , mistakenly i put that in place of as, Now it is correct.

Hi cool16,

You're absolutely right that this is an example of ellipsis. Let's take a simple sentence to see how ellipsis can work.

1. The GMAT is tougher than I thought. ← The use of ellipsis in this sentence is quite straightforward.

2. The GMAT is tougher than I thought it would be. ← The same sentence, with a few of the omitted words added.

3. The GMAT is tougher than I thought it would be tougher. ← Clearly, we can't just pick tougher up from the first half and put it in the second. Don't look at the "I thought it would be tougher" in isolation. That structure would be fine alone, but it is not correct when placed after than.

4. The GMAT is tougher than I thought it would be tough. ← This is the correct version of the sentence without any ellipsis. Again, don't look at the "I thought it would be tough" in isolation. Instead, think of it as an ~"amount", something like "how tough I thought the GMAT would be". So the sentence says that the GMAT is tougher than that ("tougher than how tough I thought it would be").

Now let's turn to the type of construction the question uses. One difference here is that we have a passive (was thought) after than. The biggest impact that this has on our analysis is that we cannot make water the subject of was thought (that is, we cannot say "water was thought"). We'll supply the words that have been omitted in a shorter (but similar) sentence.

5. More water was lost than was previously thought. ← Let's start with this sentence. This sentence is correct.

6. More water was lost than it was previously thought. ← Now we've supplied some of the missing words. This sentence is not correct though. We're not allowed to pick an arbitrary number of words to omit.

7. More water was lost than it was previously thought was lost. ← Now we've supplied enough of the missing words to make this sentence correct.

8. More water was lost than it was previously thought water was lost. ← Now we've added water in the right place.

AjiteshArun
Sorry , you did not get my point
Your example is totally different from the example in question
the example in question has a shift in verb tense .
in your example both entities in comparison are in past tense so we can ellipse verb as it will convey same tense.
But the example in question has present tense in first water and past in second , so to covey past tense in second entity we must require past verb "was" in option c , But its not there ...

for example lets take a simple example :

John is drinking more water than (is) Julie. => conveying john and julie drinking water at a same time.( same verb tense), we can omit "is " in second entity

John have drunk more water than julie did last monday => here if i omit did in second entity ,it will not convey intended meaning.

my question is what made the option c omit was and still correct

In the example you mentioned, Julie "borrows" the verb from "John". But that's the thing: option C is not an example of a tense shift.

Let's take another look at the key takeaways from the previous post: (a) the subject for was thought is it, and (b) water does not come into the picture until much later. That is, the first half does not "borrow" anything from the part before the than.

5. More water was lost than was previously thought. ← The was in was lost has nothing to do with the was in was thought. No "borrowing" going on here.
6. More water was lost than it was previously thought water was lost. ← This is where the was lost becomes relevant, when we get to water ("water was lost").

We can easily switch from the past to the present tense:

7. More water is lost than was previously thought. ← This sentence means that more water is lost (generally, on an ongoing basis) than ~"our previous estimates" of the same thing.
8. More water is lost than it was previously thought water is lost. ← This is to reinforce the fact that the is in is lost is not for was thought.

9. More water is lost than it is previously thought water is lost. ← Note how the word previously prevents us from interpreting the was in was thought as an is.

Now let's finish by removing the was, as it is not necessary. That is, with a previously, the reader understands that the idea has to be in the past tense.

10. More water is lost than previously thought.

Both these posts are quite dense, but I couldn't really tell how much detail you were looking for. If this post also didn't help, please don't hesitate to say that. Either I or someone else will give you an answer that you will find helpful.