It is currently 21 Oct 2017, 23:29

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Scientists have dated sharp-edged flakes of stone found in

Author Message
TAGS:

Hide Tags

Director
Joined: 10 Feb 2006
Posts: 660

Kudos [?]: 624 [1], given: 0

Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

03 Sep 2007, 20:47
1
KUDOS
7
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

57% (00:46) correct 43% (00:45) wrong based on 300 sessions

HideShow timer Statistics

Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago, pushing back by more than 150,000 years the earliest date when it is known that humans made stone tools.

A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make

I would think the answer should be E. ??
[Reveal] Spoiler: OA

_________________

GMAT the final frontie!!!.

Last edited by carcass on 02 Feb 2017, 07:39, edited 1 time in total.
Edited by Carcass

Kudos [?]: 624 [1], given: 0

Director
Joined: 22 Aug 2007
Posts: 566

Kudos [?]: 71 [0], given: 0

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

04 Sep 2007, 01:33
1
This post was
BOOKMARKED
Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a
dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago,
pushing back by more than 150,000 years the earliest date when it is known that humans

A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make
[/u]

I would think the answer should be E. ??

C,

.........date at which something is known to .....is correct idiom
f.e: date at which the portrait is known to have been sold...

E is unidiomatic, completely.

we can say date of event {birth, death...test} f,e: we can say date of his {her, Ann`s} birth, but 'date of ' is not used directly with people or living things.

Kudos [?]: 71 [0], given: 0

Manager
Joined: 11 Jul 2009
Posts: 52

Kudos [?]: 28 [1], given: 19

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

18 Nov 2009, 19:58
1
KUDOS
Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a
dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago,
pushing back by more than 150,000 years the earliest date when it is known that humans

A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make
[/u]

I would think the answer should be E. ??

B Had made suggested that it is not being done any more.Also it seems to refer to scientists
C correct --have dated and have made llel and earliest date at which - idiomatically correct
D to be making wrong tense and idiom
E humans who were known - changes meaning and also wrong tense

Kudos [?]: 28 [1], given: 19

Manager
Joined: 13 Oct 2009
Posts: 116

Kudos [?]: 101 [1], given: 66

Location: USA
Schools: IU KSB
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

01 Dec 2009, 08:23
1
KUDOS
Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a
dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago,
pushing back by more than 150,000 years the earliest date when it is known that humans

A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make
[/u]

I would think the answer should be E. ??

Can anyone please explain all the option of this question?

Kudos [?]: 101 [1], given: 66

Senior Manager
Affiliations: PMP
Joined: 13 Oct 2009
Posts: 296

Kudos [?]: 175 [1], given: 37

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

01 Dec 2009, 08:53
1
KUDOS
Dated at or Date at is correct idiom , so A,D, E are out

in B, "it" is ambiguous;
C looks better

hence C
_________________

Thanks, Sri
-------------------------------
keep uppp...ing the tempo...

Press +1 Kudos, if you think my post gave u a tiny tip

Kudos [?]: 175 [1], given: 37

Manager
Joined: 13 Oct 2009
Posts: 116

Kudos [?]: 101 [0], given: 66

Location: USA
Schools: IU KSB
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

01 Dec 2009, 09:08
srini123 wrote:
Dated at or Date at is correct idiom , so A,D, E are out

in B, "it" is ambiguous;
C looks better

hence C

Thanks Srini

Last edited by swatirpr on 02 Dec 2009, 20:27, edited 1 time in total.

Kudos [?]: 101 [0], given: 66

Manager
Joined: 06 Jul 2010
Posts: 101

Kudos [?]: 8 [0], given: 9

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

31 Jul 2010, 20:44
I am with C as well. Whats the OA? Please share the OA

Kudos [?]: 8 [0], given: 9

VP
Joined: 17 Feb 2010
Posts: 1475

Kudos [?]: 761 [0], given: 6

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

02 Aug 2010, 09:41
OA is C.

good question though. quite difficult to remember all the idioms.

Kudos [?]: 761 [0], given: 6

Manager
Joined: 20 Jul 2010
Posts: 185

Kudos [?]: 136 [1], given: 7

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

02 Aug 2010, 10:26
1
KUDOS
1
This post was
BOOKMARKED
date at which is the correct idiom..
Hence C
_________________

Gotta hit the 700 score this time... 3rd time lucky !
Give me some kudos... Like you, even I need them badly

Kudos [?]: 136 [1], given: 7

Manager
Joined: 12 Nov 2011
Posts: 129

Kudos [?]: 33 [0], given: 24

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

28 Jan 2012, 11:13

Kudos [?]: 33 [0], given: 24

Manager
Joined: 23 Oct 2011
Posts: 53

Kudos [?]: 69 [0], given: 7

Location: Ukraine
Schools: LBS '14 (M)
GMAT 1: 650 Q44 V35
WE: Corporate Finance (Mutual Funds and Brokerage)
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

06 May 2012, 13:51
Runner2 wrote:

I have the same question.
as per previous discussions, "have made" is || with "have dated". I think it is wrong because "have dated" referes to scientists and current time, but "have made" to people who lived thousand of years ago.

why is present perfect used?

Kudos [?]: 69 [0], given: 7

Manager
Joined: 19 Oct 2011
Posts: 129

Kudos [?]: 463 [0], given: 33

Location: India
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

07 May 2012, 18:36
1
This post was
BOOKMARKED
Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a
dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago,
pushing back by more than 150,000 years the earliest date when it is known that humans

[/u]

I would think the answer should be E. ??

A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make : speaks about time not humans.
_________________

Encourage me by pressing the KUDOS if you find my post to be helpful.

Help me win "The One Thing You Wish You Knew - GMAT Club Contest"
http://gmatclub.com/forum/the-one-thing-you-wish-you-knew-gmat-club-contest-140358.html#p1130989

Kudos [?]: 463 [0], given: 33

Senior Manager
Affiliations: UWC
Joined: 09 May 2012
Posts: 393

Kudos [?]: 1616 [0], given: 100

GMAT 1: 620 Q42 V33
GMAT 2: 680 Q44 V38
GPA: 3.43
WE: Engineering (Entertainment and Sports)
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

11 May 2012, 10:42
Code:
Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a
dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago,
pushing back by more than 150,000 years the earliest date [u]when it is known that humans
A. when it is known that humans made
C. at which humans are known to have made
D. that humans are known to be making
E. of humans who were known to make

OA:C
Background: Scientists have dated sediments. They found that the pieces of sharped-edged flakes were much older than samples previously found. This sentence structure has two parts that need to be parallel. The scientists have dated and the knowledge of the earliest date at which humans are to have made...

A: ...that humans made is not parallel to Scientists have dated INCORRECT
B: had made is also not parallel; so can be eliminated INCORRECT
C: at which humans are known to have made IS parallel to Scientists have dated CORRECT
D: to be making...not parallel INCORRECT
E: to make is not parallel because it is not in the PRESENT PERFECT tense INCORRECT

hope this helps guys....

Kudos [?]: 1616 [0], given: 100

Senior Manager
Affiliations: UWC
Joined: 09 May 2012
Posts: 393

Kudos [?]: 1616 [0], given: 100

GMAT 1: 620 Q42 V33
GMAT 2: 680 Q44 V38
GPA: 3.43
WE: Engineering (Entertainment and Sports)
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

11 May 2012, 10:56
Quote:
as per previous discussions, "have made" is || with "have dated". I think it is wrong because "have dated" referes to scientists and current time, but "have made" to people who lived thousand of years ago.

have made does not refer to to the people who lived thousands of years ago; however, it is modifying the earliest known date that is currently known (i.e the current theory, that these type of tools were only made 150,000 later)

Does this make sense?

Kudos [?]: 1616 [0], given: 100

Manager
Joined: 05 Jun 2012
Posts: 107

Kudos [?]: 16 [0], given: 66

Schools: IIMA
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

01 Aug 2014, 00:47
'Dated at' is correct idiom , also sentence conveys correct meeting C wins
_________________

If you are not over prepared then you are under prepared !!!

Kudos [?]: 16 [0], given: 66

GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10104

Kudos [?]: 264 [0], given: 0

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

12 Aug 2015, 10:50
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Kudos [?]: 264 [0], given: 0

GMAT Club Legend
Joined: 01 Oct 2013
Posts: 10104

Kudos [?]: 264 [0], given: 0

Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

19 Sep 2016, 16:06
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Kudos [?]: 264 [0], given: 0

Manager
Joined: 01 Sep 2016
Posts: 208

Kudos [?]: 172 [0], given: 33

GMAT 1: 690 Q49 V35
Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

Show Tags

04 Sep 2017, 11:46
this is one of those problems from which you can learn about the ways in which these sorts of constructions are used. indeed, it is precisely from these sorts of problems that you must learn about the niceties of these constructions, as the gmat's usage can, and does, sometimes vary from that of other sources.

in this sort of construction, i'm pretty sure that either "when" or "at which" would be acceptable. (clearly, the latter is acceptable -- it appears in the correct answer, after all -- but i wouldn't object to the former.)
if you want to get really subtle, i think (not 100% sure) that "the date when" is used for actual, precise calendar dates, whereas "the date at which" is used for the usually more vague dates of historical events, such as the one in this problem. but i'm sure the test is not going to depend on this sort of nuanced difference.

i think the real problem with the construction in choice (a) is that the clause following "when" is "it is known". in other words, that choice suggests that the fact is (was?) known at that date, an interpretation that clearly doesn't make sense in context.
in the correct answer, the "at which" is followed by a clause whose subject is "humans", and which describes the actual action that took place at that date. therefore, i think the idea is that this clause more accurately describes the chronology of the events: i.e., the toolmaking happened at that date, and the fact is known now.

as for your other question, this isn't really a perfect tense, because it's actually not a tense at all -- it's an infinitive.
probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
_________________

we shall fight on the beaches,
we shall fight on the landing grounds,
we shall fight in the fields and in the streets,
we shall fight in the hills;
we shall never surrender!

Kudos [?]: 172 [0], given: 33

Re: Scientists have dated sharp-edged flakes of stone found in   [#permalink] 04 Sep 2017, 11:46
Display posts from previous: Sort by