The Acoma and Hopi are probably the two

[RonPurewal]

RON,
present perfect makes us troubles on GMAT. Ron, could you please tell us all the cases you know, in which present perfect is used. Pls, give us example for each case.

this is an unfairly general question. (it's also an impossible question for me to answer, as i don't have this sort of thing memorized; neither would any other native speaker.)

fortunately -- as in the case of any other extremely general question -- you can get answers quickly and easily by just googling.

just google "english present perfect" and start reading the top hits.

waiting for you, Ron.

i'll thank you not to make comments like this -- comments that come off as rude or demanding.
(if that wasn't your intention, then, ok -- but the surrounding etiquette is still an important lesson to learn, especially for someone who presumably wants to go into business in an english-speaking country. this comment does look like an impatient demand: "i'm waiting for you...")

[RonPurewal]

here's a post i wrote on the general mindset behind perfect tenses:
post58397.html#p58397

[thanghnvn]

Thank you Ron. This is very tough question becaue "date" inhere makes sense only in the present tense as you said.

But I have another question.

in A, the correct choice, "both dating..." is absolute phrase, a phrase which contains a noun and its modifier.

What is the meaning (semantic) relation between main clause and the absolute phrase? inhere the relation is that the absolute phrase modifying the main clause. But in the following

his hand crippled, he is still go forward.

the relation is that the absolute phrase provides context of main clause.

Is both correct? Is it right that the meaning relation between the absolute phrase and the main clause is versatile?

[RonPurewal]

in A, the correct choice, "both dating..." is absolute phrase, a phrase which contains a noun and its modifier.

What is the meaning (semantic) relation between main clause and the absolute phrase? inhere the relation is that the absolute phrase modifying the main clause. But in the following

his hand crippled, he is still go forward.

the relation is that the absolute phrase provides context of main clause.

"providing the context of the main clause" is just one particular form of "modifying the main clause", so i'm not seeing the distinction you are trying to make here.

also, "he is still go" is not a valid construction. that's a much more fundamental issue -- you're making up verb tenses that don't exist ("is go").
if you don't yet have a command of how to form basic english verbs (NOT the subtle differences between the tenses -- just how to form the basic tenses), then you should definitely get that figured out before you start considering modifiers and such things.

[nowwithgmat]

hello instructor
in option A is "(comma) , both dating ..........." participle modifier..??

[tim]

sure. does that matter though?

[nowwithgmat]

sure. does that matter though?

thax tim

[tim]

i'll take that as a "no" :)

[xyq121573]

i am not a good master of tense,however,i eliminate B in the following reasoning: which here is not appropriate, because it modifies communites and doesn't have correspondence with are probably the two oldest....
for example: I love this painting,which was drawn by Gogh.
here, which was drawn by Gogh modifies painting but has no correspondence with love.
However, in this question, the clause has the intended meaning that date back at least a thousand years should modify are probably the two oldest... so B is wrong,or at least worse than A
am i correct? thx in advance~

[RonPurewal]

i am not a good master of tense,however,i eliminate B in the following reasoning: which here is not appropriate, because it modifies communites and doesn't have correspondence with are probably the two oldest....

that construction says "the two oldest communities". so, anything modifying this noun is, by definition, only talking about the two oldest communities.

[Suapplle]

Hi,Ron,I remember that generally,we can use "comma+v-ing" under two circumstances
First,an immediate,and basically inevitable consequence
Second,describe a simultaneous action.
So,in this case,besides these two circumstances,it can provide additional information?please certify,thanks!

[RonPurewal]

Hi,Ron,I remember that generally,we can use "comma+v-ing" under two circumstances
First,an immediate,and basically inevitable consequence
Second,describe a simultaneous action.
So,in this case,besides these two circumstances,it can provide additional information?please certify,thanks!

Coincidentally, I just wrote a post about this exact thing today. Read it here:
post94094.html#p94094

Whenever you think about this kind of stuff, remember that these constructions -- in some way or another -- need to be able to express any idea that anyone might ever want to write. That's a big job, so lots of constructions are going to have multiple functions.

[1009918171]

(b) and (c) are incorrect because of the tense used; "has dated" implies that this is not the case anymore. (this particular construction really only makes sense in the present tense -- or as an -ing modifier attached to a present-tense clause, since -ing modifiers adopt the tense of the clause to which they are attached.)

Hi, Ron!
I'm still a little confuse about the usage of the present perfect tense. I've seen a few problems that use the construction " has dated", the present perfect tense.

From GMAT prep :
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

B. at which it is known that humans had 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

From GMAT prep:
Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on (CORRECT)
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

These problems use the past perfect tense and are correct. Why?

Thanks a lot in advance!

[RonPurewal]

Yeah, the usage of those tenses is different for these 2 different kinds of verbs:
1/ Actions that happen at a specific point in time
2/ Actions that represent states (= that last for a certain duration)

If you imagine a timeline as a literal graph, then #1 represents actions that would be points or dots on that number line, while #2 represents states that would be linear portions on that number line.

#1: E.g., Scott graduated from high school.
This is not an ongoing state. It's something that happens at one exact moment (the moment of graduation).

#2: E.g., Scott was married (for ten years).
Ongoing for a duration of 10 years.

See below for how you use "has/have VERBed" with these.

[RonPurewal]

Type 1/
If it's a point thing, then "has/have VERBed" means ...
... it happened,
... it's somehow relevant to the present.

E.g.,
People who have graduated from high school usually find employment much more easily than people who have not.
They've graduated (at any time). We don't know when"”maybe yesterday, maybe 40 years ago.
Regardless, it's relevant to the present; we're talking about their job prospects at present.

These are past events, seen through the lens of the present.
They are not 'continuing up to the present', because these verbs represent things that CANNOT 'continue'. they happen at one exact point in time, and ... that's it.