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

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

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03 Sep 2007, 20:47
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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

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Last edited by carcass on 02 Feb 2017, 07:39, edited 1 time in total.
Edited by Carcass
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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04 Sep 2007, 01:33
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.
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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18 Nov 2009, 19:58
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
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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01 Dec 2009, 08:23
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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?

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

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

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

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

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

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31 Jul 2010, 20:44
I am with C as well. Whats the OA? Please share the OA
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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02 Aug 2010, 09:41
OA is C.

good question though. quite difficult to remember all the idioms.
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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02 Aug 2010, 10:26
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date at which is the correct idiom..
Hence C
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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28 Jan 2012, 11:13
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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

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07 May 2012, 18:36
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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.
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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

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

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01 Aug 2014, 00:47
'Dated at' is correct idiom , also sentence conveys correct meeting C wins
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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12 Aug 2015, 10:50
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Re: Scientists have dated sharp-edged flakes of stone found in [#permalink]

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

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Re: Scientists have dated sharp-edged flakes of stone found in   [#permalink] 19 Sep 2016, 16:06
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