Rock samples

[RonPurewal]

Also -- Without a timeframe, "has/have __ed" almost always refers to past events (with some relevance to the present).
The meaning of "ongoing up to the present" is generally restricted to sentences with an explicit timeframe.

E.g.,

James has had the flu for 5 days.
--> He's had a cold for the last 5 days, up to now. (He may still have a cold; he may have just gotten over it.)

James has had the flu.
--> He's had it at some point in the past (and it's relevant now -- e.g., people are discussing flu shots, or whatever).

So, in this sentence, "... has been evidence" implies that these things were once evidence, but are no longer evidence. Hmm. Nope.

[ShriramC110]

Hi Ron,

So just for my understanding,
Isn't the "have been dated" in the answer choices little absurd.
Doesn't it show that the act of dating started in the past and it's still ongoing???

Thanks

[RonPurewal]

Doesn't it show that the act of dating started in the past and it's still ongoing???

no.
please read the thread.

in fact, this is already addressed in the post directly above yours.

[RonPurewal]

and this...

Isn't the "have been dated" in the answer choices little absurd.

...is in the correct answer.

DO NOT question the correct answers!

here's a handy FAQ:

Q: Is the correct answer correct?
A: Yes.

Q: Is the correct answer wrong?
A: No.

Q: I disagree with the correct answer. Who's wrong, me or GMAC?
A: You.

Q: I wrote this other version. Is it better than the correct answer?
A: No.

[DiJ92]

Also -- Without a timeframe, "has/have __ed" almost always refers to past events (with some relevance to the present).
The meaning of "ongoing up to the present" is generally restricted to sentences with an explicit timeframe.

E.g.,

James has had the flu for 5 days.
--> He's had a cold for the last 5 days, up to now. (He may still have a cold; he may have just gotten over it.)

James has had the flu.
--> He's had it at some point in the past (and it's relevant now -- e.g., people are discussing flu shots, or whatever).

So, in this sentence, "... has been evidence" implies that these things were once evidence, but are no longer evidence. Hmm. Nope.

Dear Ron
As you said, without a time frame, "has/have done" almost always refers to past events. Why is "Have been dated at" correct？ My understanding is that the action" be dated at 3.47 billion years old" happened in the past, and it does not happen any more because if now the rock samples are dated, they will be more than 3.47 billion years old. Am I right?

[RonPurewal]

well, "3.47 billion years" doesn't mean EXACTLY 3,470,000,000 years, 0 months, 0 days, 0 hours, 0 minutes, and 0 seconds. it's an approximate figure.

if i have a fossil that's 3.47 billion years old, then...
...a thousand years ago, it was 3.47 billion years old;
...last year it was 3.47 billion years old;
...right now it's 3.47 billion years old;
...100 years from now it will be 3.47 billion years old;
...10,000 years from now it will be 3.47 billion years old.

you get the point.
this is why 'has been...' works here: because '3.47 billion years' is going to be the correct age for such a long time that we can essentially treat it as permanent.

[RonPurewal]

also—MUCH MORE IMPORTANTLY—this is a non-issue here.
all five choices have the same tense (has been / have been). the only issue there is subject-verb (dis)agreement.

[RonPurewal]

...and, finally, this is an OG problem.

no further discussion will be allowed here until a screenshot is posted as proof that this problem is actually in the FREE GMAT PREP software.

if any further posts are made without such a screenshot, they will be summarily deleted.
thank you.