Gmat

[xyin]

Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.
(GMAT prep verbal section)
A. a reasonably clear picture has emerged of the patterns and causes of ocean currents
B. a reasonably clear picture of the patterns of ocean currents and their causes have emerged
C. a reasonably clear picture emerged of ocean currents, their patterns and the causes of them
D. there have emerged a reasonably clear picture of the patterns of ocean currents and what caused them
E. there had emerged a reasonably clear picture of the patterns of ocean currents and their causes

The non-underlined sentence shows us "in the last half century" that is suppose to be a sign of past tense. But why we still need to use present perfect tense. Can anyone help me answer this one? Thanks.

[kvitkod]

Present perfect expresses an action that began in the past and which HAS RECENTLY BEEN COMPLETED OR CONTINUES INTO THE PRESENT. According to the passage either of the above is applicable to the "reasonably clear picture".

By the way, the sole option with past simple (c) has a problem with pronounces.

[ranjeet1975]

Yes Present Perfect is used when the action hs started in Past and is still continuing or the effect of the past action is still continuing the present

The use of Present Perfect is right here.

[hi]

A. a reasonably clear picture has emerged of the patterns and causes of ocean currents
there seems no problem. Keep it.
B. a reasonably clear picture of the patterns of ocean currents and their causes have emerged
have is incorrect. It should be a clear picture has emerged.
C. a reasonably clear picture emerged of ocean currents, their patterns and the causes of them
it seems as if clear picture of ocean currents, their patters and the causes emerged.
D. there have emerged a reasonably clear picture of the patterns of ocean currents and what caused them
usage of 'have' seems to be wrong. Moreover, the usage should be 'there has emerged a ...'
E. there had emerged a reasonably clear picture of the patterns of ocean currents and their causes
usage of had is incorrect.

OA - A.

[RonPurewal]

The non-underlined sentence shows us "in the last half century" that is suppose to be a sign of past tense. But why we still need to use present perfect tense. Can anyone help me answer this one? Thanks.

actually, "in the last half-century" REQUIRES the present perfect, because it's an indefinite period of time that extends up to the present.
similarly, you must use the present perfect with any of the following constructions:
"within the last (TIME PERIOD)..."
"since (DATE)..."
"for the last (TIME PERIOD)..."

[sachin.w]

Hi Ron,
I feel the meaning is not clear in A.. as the picture that has emerged is of the patterns and not also about their causes..

B has the issue of 'have'..
Kindly explain..
Regards,
Sachin

[jlucero]

Hi Ron,
I feel the meaning is not clear in A.. as the picture that has emerged is of the patterns and not also about their causes..

B has the issue of 'have'..
Kindly explain..
Regards,
Sachin

(A) Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the (patterns and causes) of ocean currents.

Patterns and causes are parallel, so you could repeat this sentence once with the word patterns in the sentence and once with the word causes. Therefore, there are patterns of ocean currents and causes of ocean currents. Perfectly acceptable.

As for B, do you have a question or just pointing out the error?

[sachin.w]

Hi Ron,
I feel the meaning is not clear in A.. as the picture that has emerged is of the patterns and not also about their causes..

B has the issue of 'have'..
Kindly explain..
Regards,
Sachin

(A) Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the (patterns and causes) of ocean currents.

Patterns and causes are parallel, so you could repeat this sentence once with the word patterns in the sentence and once with the word causes. Therefore, there are patterns of ocean currents and causes of ocean currents. Perfectly acceptable.

As for B, do you have a question or just pointing out the error?

Thanks Joe,
What I am actually trying to say is that a picture can contain patterns and not their causes. How could a picture portray causes of something ? And so, I feel the meaning isn't clear in A.

[Willy]

sachin.w, you are taking the meaning of 'picture' in literal sense when sentence is implying something else.

Read the sentence once again and you will get what it is actually saying. Here picture is not equal to photograph that you are interpreting. In this sentence 'picture' means 'idea', 'description' or something like that. (i am sorry for not being able to convey it properly but surely here picture =/= photograph)

Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.

[sachin.w]

sachin.w, you are taking the meaning of 'picture' in literal sense when sentence is implying something else.

Read the sentence once again and you will get what it is actually saying. Here picture is not equal to photograph that you are interpreting. In this sentence 'picture' means 'idea', 'description' or something like that. (i am sorry for not being able to convey it properly but surely here picture =/= photograph)

Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.

You are right. Thanks Willy!

[tim]

let us know if there are any further questions on this one..

[crusade]

Hi,

Isnt the construction of A a bit awkward? A reasonable picture has emerged of..

Shouldnt the "of" part of the clause be after "reasonable"?

So " A reasonable picture of..has emerged"

Am I missing something here?

[tim]

first --
OFFICIALLY CORRECT ANSWERS ARE CORRECT!
do not question officially correct answers!
far too many students on this forum make the mistake of questioning the correct answers; please note that doing so is a complete waste of your time and effort. i.e., exactly 0% of the time that you spend posting "isn't this official answer wrong?" is productive, and exactly 100% of that time is wasted.

"is this correct?" is never a productive question to ask about one of GMAC's correct answers. the answer is always yes.
"is this wrong?" / "is this X type of error?" is never a productive question to ask about one of GMAC's correct answers. the answer is always no.

instead, the questions you should be asking about correct official answers, if you don't understand them, are:
"why is this correct?"
"how does this work?"
"what understanding am i lacking that i need to understand this choice?"

this is a small, but hugely significant, change to your way of thinking.
you will suddenly find it much easier to understand the format, style, and conventions of the official problems if you retire the idea that they might be wrong.

As for your question, there is nothing wrong with an answer choice sounding "wordy" or "awkward". In fact, I have NEVER seen a GMAT problem for which the only way to eliminate an answer is awkwardness. If you ever use the phrase "wordy and awkward" (or anything else that sounds similar) to explain your reasoning on a SC question, you have done something wrong. If you are willing to eliminate an answer choice because it is awkward, you may end up eliminating the correct choice. There is ALWAYS a real reason why SC answer choices are wrong, and "wordy and awkward" is NEVER that reason. Please note that if you read an explanation that uses the words "awkward" or "wordy", that explanation is wrong - EVEN IF IT IS A DIRECT QUOTE FROM THE OFFICIAL GUIDE.

[270699172]

hi tim,
in answer A, "has emerged" is inserted into "clear picture" and "of the patterns and causes", but noun 1 of noun 2 is not allowed to be separated. i'm confused. So i think b is better than a.

[tim]

I take it you haven’t read the whole thread, because you still seem to be questioning the correct answer. I’ll be glad to help you further with this one if you can tell me where you have encountered a rule that allows you to eliminate A AND you can tell me why you think "a reasonably clear picture ... have emerged" is acceptable in B.