Helping verbs in different tenses

[magic monkey]

It is said in Manhattan5th p235 as the following:

The first instance of the verb should usually match the helping verb in tense. If you need to change tenses, repeat the whole verb in the new tense.
Wrong: I have never seen an aardvark, but last year my father DID.
Right: I have never seen an aardvark, but last year my father saw one.

BUT,
in OG13-sc-125, "did" in the correct sentence of "Today, because of ..., the same ... acreage produces twice as ... as it did in 1910." violates this rule.
(I know it's not allowed to quote the OG sentences, so just put on the main structure. Is that ok?)

So which one is right? Or just there's some specific reason for the difference between this rule and the official correct sentence?

For a furthur disscussion, I've listed several sentences below, which are slightly different with each other. Could you please tell me WHICH one and WHY is correct or not? Thanks a lot!

I have never seen an aardvark, but last year my father saw one.
I have never seen an aardvark, but last year my father did.
I have never seen an aardvark, but next year I may see one.
I have never seen an aardvark, but next year I may do.
I have never seen more aardvarks than I saw last year.
I have never seen more aardvarks than I did last year.


It might not be very important during the test, but I'm just curious about the real fact within it. Could you help me to clarify it?

[Jim@StratusPrep]

The key word in the the M GMAT phrase is SHOULD USUALLY match...

In the example you are matching have never seen to saw.


In the OG, a more correct answer might be 'produced' instead of 'did' but that does not mean the example is wrong, just not the best possible answer.

[e-GMAT]

@ magic monkey,
First of all I would suggest that you consider this statement as a guideline and not a hard and fast rule. Please understand the distinction between the rules such as "subject and verb must always agree in number" and the guidelines such as the one in discussion. While you should eliminate choices based on the rules, you should consider the guidelines just as "guidelines".

Now I am not saying that the sentence in question violates the stated guideline. For this lets first understand the basis of the guideline in question. Basically, this originates from the general principle of omission of words in a sentence. Such omission (also called as ellipsis) is done to make the sentence more crisp. Typically we do not repeat certain words that have already appeared once in the sentence. This applies really well when we have comparison or parallel constructions involving verbs. For example, lets take the first example sentence that you have quoted from MGMAT:

I have never seen an aardvark, but last year my father DID.
Now this sentence is wrong. And here is why. Here ellipsis/omission has not been applied correctly. Basically the author has omitted the verb - see. (did see = saw)

I have never seen an aardvark, but last year my father DID SEE.
But notice, the verb "see" does not appear as is anywhere in the sentence. And you cannot omit something that does not exist.

Now lets take the OG sentence:
Today, because of ..., the same ... acreage produces twice as ... as it did in 1910.
This sentence is correct as is. Lets see how omission is correctly applied here: Basically the author intends to say the following (focus on the blue text)

Today, because of ..., the same ... acreage produces twice as ... as it did produce in 1910.
Now the word "produce" appears in the sentence (yes it is in singular case but it is in the same verb form - produce) And this is why this sentence is correct, since we have simply omitted the main verb and this main verb appears in the same verb form elsewhere in the sentence.

Lets take one more official sentence:
Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were last year.

In this sentence as well, the verb form "paying" has been omitted. And this is correct since it appears in same form elsewhere in the sentence.

I hope this helps.

Regards,

Payal

[magic monkey]

@ magic monkey,
First of all I would suggest that you consider this statement as a guideline and not a hard and fast rule. Please understand the distinction between the rules such as "subject and verb must always agree in number" and the guidelines such as the one in discussion. While you should eliminate choices based on the rules, you should consider the guidelines just as "guidelines".

Now I am not saying that the sentence in question violates the stated guideline. For this lets first understand the basis of the guideline in question. Basically, this originates from the general principle of omission of words in a sentence. Such omission (also called as ellipsis) is done to make the sentence more crisp. Typically we do not repeat certain words that have already appeared once in the sentence. This applies really well when we have comparison or parallel constructions involving verbs. For example, lets take the first example sentence that you have quoted from MGMAT:

I have never seen an aardvark, but last year my father DID.
Now this sentence is wrong. And here is why. Here ellipsis/omission has not been applied correctly. Basically the author has omitted the verb - see. (did see = saw)

I have never seen an aardvark, but last year my father DID SEE.
But notice, the verb "see" does not appear as is anywhere in the sentence. And you cannot omit something that does not exist.

Now lets take the OG sentence:
Today, because of ..., the same ... acreage produces twice as ... as it did in 1910.
This sentence is correct as is. Lets see how omission is correctly applied here: Basically the author intends to say the following (focus on the blue text)

Today, because of ..., the same ... acreage produces twice as ... as it did produce in 1910.
Now the word "produce" appears in the sentence (yes it is in singular case but it is in the same verb form - produce) And this is why this sentence is correct, since we have simply omitted the main verb and this main verb appears in the same verb form elsewhere in the sentence.

Lets take one more official sentence:
Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were last year.

In this sentence as well, the verb form "paying" has been omitted. And this is correct since it appears in same form elsewhere in the sentence.

I hope this helps.

Regards,

Payal

Thanks! It helps to make me a litte clear on this point.

but I've still got some questions about this guideline.
"The first instance of the verb should usually match the helping verb in tense. If you need to change tenses, repeat the whole verb in the new tense."

as what you've said, the real point is that "we do not repeat certain words that have already appeared once in the sentence", not that it's necessary to repeat the whole verb in the new tense.
please correct my words if I'm wrong.

so, no doubt I should repeat saw/see in the second clause.
Right:
I have never seen an aardvark, but last year my father saw one.
I have never seen an aardvark, but next year I may see one.
I have never seen more aardvarks than I saw last year.

BUT, what if a verb doesn't change its verb form a lot in different tenses. Take "produce" for instance:
(a simple form rewritten from the OG sentence above)
BM produces twice as many cars as it did last year. --- as in the OG, correct.

what about the following two?
BM will produce twice as many cars as it did last year. ---?
BM has produced twice as many cars as it did last year. ---?

if these two are right, I really doubt whether there's a point for the guideline to exist. The key should be to omit the repeated verbs and phrases.
if these two are wrong, then what's the difference with the first one from OG?

[lunarpower]

i received a private message about this thread.

It is said in Manhattan5th p235 as the following:

The first instance of the verb should usually match the helping verb in tense. If you need to change tenses, repeat the whole verb in the new tense.

this is not true. if our strategy guide says this, we need to edit it -- i'll submit that to the committee that revises the strategy guides.

in general,
* if you use did/do/does/etc. to stand for an action verb, then it can be parallel to any tense of that action verb.
e.g., you can use "did" in parallel to saw (which is in the same tense), but you can also use it in parallel to has/have seen, will see, sees, etc.

so, for instance,
No one else will ever play that piece as well as you did last night.
--> this sentence is perfectly correct, as is the one about acreage in the OG.

--

on the other hand, there may be instances in which you can't use "did" because it would create an unintended alternate meaning.
for instance, let's say you saw something, and now other people are looking for the thing you saw but can't find it.
then you would want to write:
Nobody else sees what you saw.
in this particular instance, you can't write Nobody else sees what you did -- not because there's a helping verb issue, but because that sentence appears to be saying something altogether different. specifically, that version seems to suggest that you did something (e.g., broke a glass, or something), but that no one else can see the evidence.

[lunarpower]

I have never seen an aardvark, but last year my father saw one.
I have never seen an aardvark, but last year my father did.
I have never seen an aardvark, but next year I may see one.
I have never seen an aardvark, but next year I may do.
I have never seen more aardvarks than I saw last year.
I have never seen more aardvarks than I did last year.

all of these are fine except the fourth one. that one is incorrect because it contains two consecutive helping verbs ("may" and "do"); you can't use more than one helping verb.

[magic monkey]

i received a private message about this thread.

It is said in Manhattan5th p235 as the following:

The first instance of the verb should usually match the helping verb in tense. If you need to change tenses, repeat the whole verb in the new tense.

this is not true. if our strategy guide says this, we need to edit it -- i'll submit that to the committee that revises the strategy guides.

in general,
* if you use did/do/does/etc. to stand for an action verb, then it can be parallel to any tense of that action verb.
e.g., you can use "did" in parallel to saw (which is in the same tense), but you can also use it in parallel to has/have seen, will see, sees, etc.

so, for instance,
No one else will ever play that piece as well as you did last night.
--> this sentence is perfectly correct, as is the one about acreage in the OG.

--

on the other hand, there may be instances in which you can't use "did" because it would create an unintended alternate meaning.
for instance, let's say you saw something, and now other people are looking for the thing you saw but can't find it.
then you would want to write:
Nobody else sees what you saw.
in this particular instance, you can't write Nobody else sees what you did -- not because there's a helping verb issue, but because that sentence appears to be saying something altogether different. specifically, that version seems to suggest that you did something (e.g., broke a glass, or something), but that no one else can see the evidence.

Thanks, Ron!

But I've seen another explanation on comparison (my friend quotes that as from you...)
Could you tell me what's the difference in the following one:

...
2 * if you have than/as + subject + HELPING VERB as the second half of a comparison, then you must have the SAME helping verb (perhaps in a different tense) in the first half of the comparison.

here are some examples:

i can run much faster than i could before my most recent knee operation. (note that "could" is the past tense of "can", so these are the same helping verb.)

does it mean that it's not ok when i say,
I ran much faster than i could before my first knee operation.

could you give me more information on this? thanks~

[magic monkey]

I have never seen an aardvark, but last year my father saw one.
I have never seen an aardvark, but last year my father did.
I have never seen an aardvark, but next year I may see one.
I have never seen an aardvark, but next year I may do.
I have never seen more aardvarks than I saw last year.
I have never seen more aardvarks than I did last year.

all of these are fine except the fourth one. that one is incorrect because it contains two consecutive helping verbs ("may" and "do"); you can't use more than one helping verb.

I get this point now, thanks:)
just don't know if there are some more points in comparison to which i should pay attention.

[lunarpower]

just don't know if there are some more points in comparison to which i should pay attention.

nah. in fact, you may already be looking for way more than you actually have to see.

remember, the gmat problems don't ask you to give a cold judgment of whether things are right or wrong by themselves.
instead, you face a far more limited task, which is to compare the answer choices relative to each other.

what this means, in practical terms, is that you shouldn't ever have to face extremely subtle issues. more often than not, if you see something that you think is extremely difficult to judge, there will probably be something about the other choices that makes the decision a lot easier.

for instance, consider the OG "acreage" problem (which i'm not allowed to reproduce here).
even if you have some initial misgivings about the "did", that should all go away as soon as you look at the alternatives, which are quite clearly worse than "did".

don't forget -- you don't have to judge five individual answer choices. you just have to pick the winner of a beauty contest, which is a lot easier than trying to decide how individually beautiful the five choices are.

[lunarpower]

in fact --

nah. in fact, you may already be looking for way more than you actually have to see.

(yes, i just quoted myself)

as proof of the statement above, i wasn't consciously aware of any of the "rules" i've written on this thread... well... until reading this thread. and not only have i been teaching standardized tests for about 20 years, but i'm also a professional writer.

what that means, for you, is that you don't have to know this level of detail either. remember, you just have to pick the choice that does the job better than the others.

[iongmat]

on the other hand, there may be instances in which you can't use "did" because it would create an unintended alternate meaning.
for instance, let's say you saw something, and now other people are looking for the thing you saw but can't find it.
then you would want to write:
Nobody else sees what you saw.
in this particular instance, you can't write Nobody else sees what you did

Ron, can you cite any official example where you noticed that the usage of "did" created unintended alternate meaning. Would help us relate better.

[magic monkey]

just don't know if there are some more points in comparison to which i should pay attention.

nah. in fact, you may already be looking for way more than you actually have to see.

remember, the gmat problems don't ask you to give a cold judgment of whether things are right or wrong by themselves.
instead, you face a far more limited task, which is to compare the answer choices relative to each other.

what this means, in practical terms, is that you shouldn't ever have to face extremely subtle issues. more often than not, if you see something that you think is extremely difficult to judge, there will probably be something about the other choices that makes the decision a lot easier.

for instance, consider the OG "acreage" problem (which i'm not allowed to reproduce here).
even if you have some initial misgivings about the "did", that should all go away as soon as you look at the alternatives, which are quite clearly worse than "did".

don't forget -- you don't have to judge five individual answer choices. you just have to pick the winner of a beauty contest, which is a lot easier than trying to decide how individually beautiful the five choices are.

I see ... You are right. I may get far deeper than already enough.
I think what you tried to tell me is about the right mindset for GMAT, which is much more important than those details.
Great thanks for the warning!

For helping verbs, i think i just need to know the following:

in general,
* if you use did/do/does/etc. to stand for an action verb, then it can be parallel to any tense of that action verb.
e.g., you can use "did" in parallel to saw (which is in the same tense), but you can also use it in parallel to has/have seen, will see, sees, etc.

right?

[lunarpower]

Ron, can you cite any official example where you noticed that the usage of "did" created unintended alternate meaning. Would help us relate better.

sorry, i don't have any way of looking that up.

--

by the way, what do you mean by your last comment ("help us relate better")?

in general, it should be the other way around -- you should be able to relate much more easily to simple examples than to the official problems (which are, for the most part, complex sentences with lots of stuff going on).

[lunarpower]

For helping verbs, i think i just need to know the following:
...
right? :)

this is closer to the right attitude.

in general, you shouldn't be seeing a ton of complexity or subtlety in the individual ideas tested in gmat sentence correction. instead, the complexity/challenge of the problems generally stems from their use of lots of different concepts at once.

[magic monkey]

For helping verbs, i think i just need to know the following:
...
right?

this is closer to the right attitude.

in general, you shouldn't be seeing a ton of complexity or subtlety in the individual ideas tested in gmat sentence correction. instead, the complexity/challenge of the problems generally stems from their use of lots of different concepts at once.

I'll keep these words:)