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# Rock samples taken from the remains of an asteroid about twice the

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Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.
(A) has been dated to be 3.47 billion years old and thus is
(B) has been dated at 3.47 billion years old and thus
(C) have been dated to be 3.47 billion years old and thus are
(D) have been dated as being 3.47 billion years old and thus
(E) have been dated at 3.47 billion years old and thus are

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Concept tested: Idioms, SV agreement
Difficulty Level: Moderate
Illustration: "Rock samples" is the subject for the verb "has been dated". Rock samples must take a plural verb.
So A and B can be instantly eliminated.
Dated at is the correct idiomatic construction.
So C and D are also eliminated
E is the correct answer choice
Tip: Though "dated at" is preferred to "dated to be", the same construction is not necessarily true for "estimated at" and "estimated to be" construction.
"Estimated at" should be followed by a noun because "at" is a preposition.
E.g: The molten iron is estimated at 1500 degrees Celsius.
"Estimated to be" generally follows phrases
E.g: The fossil is estimated to be 1000 years old.
This is NOT a specific English rule, but the way GMAT wants things to be
Support is given by:
In OG 12 , Q 27 of SC, it says that the correct idiom is "estimated to be".
However this question appears in gmatprep
"With surface temperatures estimated at minus 230 degrees Farenheit, Jupiter's moon Europa has long been considered far too cold to support life, and with 60 square miles of water though to be frozen from top to bottom."

We can see from the non underlined part that "estimated at" is also as correct idiom.
Takeaway: Same rules do not apply to "estimated to be" and "dated to be"

answered Jun 3, 2017 by Beginner (21 points)
selected Aug 15, 2017 by
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Concept tested: Idioms, SV agreement
Difficulty Level: Moderate
Illustration: "Rock samples" is the subject for the verb "has been dated". Rock samples must take a plural verb.
So A and B can be instantly eliminated.
Dated at is the correct idiomatic construction.
So C and D are also eliminated
E is the correct answer choice
Tip: Though "dated at" is preferred to "dated to be", the same construction is not necessarily true for "estimated at" and "estimated to be" construction.
"Estimated at" should be followed by a noun because "at" is a preposition.
E.g: The molten iron is estimated at 1500 degrees Celsius.
"Estimated to be" generally follows phrases
E.g: The fossil is estimated to be 1000 years old.
This is NOT a specific English rule, but the way GMAT wants things to be
Support is given by:
In OG 12 , Q 27 of SC, it says that the correct idiom is "estimated to be".
However this question appears in gmatprep
"With surface temperatures estimated at minus 230 degrees Farenheit, Jupiter's moon Europa has long been considered far too cold to support life, and with 60 square miles of water though to be frozen from top to bottom."

We can see from the non underlined part that "estimated at" is also as correct idiom.
Takeaway: Same rules do not apply to "estimated to be" and "dated to be"

answered Jun 22, 2017 by Beginner (21 points)
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Hi Krishna,
Could you please assess my structural analysis of the sentence -
"Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth."
As there is a comprison is this sentence between two asteroid, i have marked two asteroids as asteroid 1 and asteroid 2.
Rock samples - Subject
taken from the remains of an asteroid1 - Noun modifier (type past participle) modifying Rock samples
about twice the size of the 6-mile-wide asteroid2 - Noun modifier modifying asteroid1
that eradicated the dinosaurs - Noun modifier modifying asteroid 2
has been dated to be (verb)
3.7 billion years old (object)
and thus (coordinator)
evidence of the earliest known asteroid impact on Earth (subject)
answered Jun 22, 2017 by Beginner (21 points)
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Jyotsna Mehta