Around 1900, fishermen in the Chesapeake Bay area landed more than

ExpertsGlobal5, can you please clarify your response for this sentence?
Around 1900, fishermen in the Chesapeake Bay area landed more than seventeen million pounds of shad in a single year, but by 1920, over-fishing and the proliferation of milldams and culverts that have blocked shad migrations up their spawning streams had reduced landings to less than four million pounds.

1st event: over-fishing and the proliferation of milldams and culverts had reduced--> we use past perfect tense because it happened before fishermen in the Chesapeake Bay area landed ;
2nd event: fishermen in the Chesapeake Bay area landed .

In your response , you noted that fisherman landing is the first event. So, why do we use past perfect tense for the second clause ( milldams and culverts that have blocked shad migrations up their spawning streams had reduced).
ExpertsGlobal5, GMATNinja, is there an example of the question when we use by, but don't require usage of past perfect tense?

The key point is that "by 1920" implies a past action: the starting of the year 1920. In other words, "by 1920" basically means "by the time the year 1920 began":



On a timeline, you could point to the specific moment in time when 1920 began. The action of reducing, however, took place in the period between 1900 and 1920. So we have two past actions happening at different times in the past: 1) 1920 began and 2) the proliferation had reduced. The use of the past perfect logically implies that the "reducing" happened before 1920 began.

We've written several other posts on this thread about the usage of the past perfect, so check these out if you are still confused:

1) https://gmatclub.com/forum/around-1900- ... l#p2414841
2) https://gmatclub.com/forum/around-1900- ... l#p2689448
3) https://gmatclub.com/forum/around-1900- ... l#p2741548

And, no, "by [some time]" isn't always used in this way. For example:

"Tim hopes to buy a beach house by 2030."

Clearly we wouldn't use past perfect here, since we're talking about a time in the future.

Even if we are only talking about using "by" with a time in the past, can we safely say that past perfect is always required? Would the GMAT consider something like this wrong?

"By 1970, all hope was lost."

Frankly, it's hard to say. the timing of the events isn't confusing at all, so do we really NEED the past perfect? Would the GMAT really ask us to choose between "was lost" and "had lost" without any other decision points? That seems incredibly unlikely. As described in this post (also the first link above):

Don't overthink past perfect usage. If you see "had", all you're asking is yourself is whether the action in question took place before something else in the past. If it did, "had" is acceptable.

In other words, don't try to turn this into a mindless rule about when to use past perfect. Instead, with each unique answer choice, you have to think carefully about whether the verb tense makes sense and is justifiable.

For more on the subtleties of verb tenses on the GMAT, check out this video.

I hope that helps!
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I need some help in understanding the usage of ''having+ past participle''

My understanding is that ''having + past participle'' can also take a role of a past perfect tense in a sense that it can refer to the action in the greater past. Eg: ''Having completed my bachelors, I did my masters'' I hope this sentence is not wrong. Both actions are past events, ''having'' is used in greater past.

Of course, as per my understanding, there are other usages of ''having +past participle'' such as ''Having done my homework, I can now go for a play''. I hope this sentence is also correct.

However, in this question, my specific confusion is the usage of ''X and Y having blocked''. X represents overfishing and Y represents proliferation. In such usage, will ''having'' modify both X and Y or only Y?

In the correct answer, it seems that usage of ''that blocked'' introduces touch rule of ''that'' modifier and thus should modify only the proliferation, for that also makes a logical sense.

Is above understanding, correct?

Expert opinion on this matter would be helpful.

Regards
Vighnesh Kamath

I need an expert validation on my understanding that ''having+ past participle'' is often used for indicating purpose driven cause-effect relationship. Something on the lines of infinitive of purpose.

Is the understanding correct, could this logic be used to eliminate options containing ''having'' in below answer options?

Regards
Vighnesh

Hi Vignesh, the relative pronoun "that" regularly modifies faraway nouns/phrase, based upon what makes logical sense.

Also, it's perhaps worth remembering that the structure Noun + having + past participle, is generally an incorrect construct on GMAT.

p.s. Our book EducationAisle Sentence Correction Nirvana discusses modifier framework of "that", its application and examples in significant detail. If you or someone is interested, PM me your email-id; I can mail the corresponding section.
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Hello VIGHNESHKAMATH,

We hope this finds you well.

To answer your query, the "having + past participle" construction can convey a cause-effect relationship, but does not always do so.

As such, it would be best to not use this understanding as a concrete rule for eliminating answer choices; rather, pay attention to the context and full construction of the phrase to see if a cause-effect relationship is indeed implied.

We hope this helps.
All the best!
Experts' Global Team
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Hello VIGHNESHKAMATH,

We hope this finds you well.

To answer your query, the construction "having + past participle" does imply that the action it refers to took place before another, typically the action taken by the noun it modifies; thus, if the action in question is one that concluded in the past, this construction will indicate the "greater past".

Further, if used to modify an "X + Y" construction, the "having + past participle" will modify both X and Y.

We hope this helps.
All the best!
Experts' Global Team
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I have a question on this...

I am mostly ok with B as an answer. But shouldn't the "had reduced" be "have reduced"

overfishing AND the proliferation of milldams implies a compound subject for which the verb should be plural. What am I thinking that is wrong here?

Hi gmatmba12,

Generally speaking, we need to worry about singular/plural forms only if we're dealing with the present (simple/continuous/perfect) tense. Had reduced is past perfect, so the verb won't change form. If we wanted to use the present perfect, we would need to decide between has reduced and have reduced.
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Hello gmatmba12,

We hope this finds you well.

To answer your query, the past perfect tense does not have different plural and singular forms; the "had + past participle" structure is used for both singular and plural nouns.

We hope this helps.
All the best!
Experts' Global Team
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"Having + past participle" is a pretty rare construction on the GMAT, but yeah, your understanding of the timing of the action is correct. If you see "Having devoured every taco in a 15-mile radius, Tim went to sleep, knowing he and his digestive system would be awake shortly," it's fair to say that Tim "devoured" before he "went to sleep."

However, in the official question, both the "having" modifier and the "that" appear to be describing "milldams and culverts." Overfishing can lead to various consequences, but it can't itself block fish from swimming anywhere.

Last, there is no touch rule. The only rule is that the noun modifier needs to be both logical and reasonably close to what it modifies. That's it. Here, the logical entities that would block the fish are the "milldams and culverts," which happen to be right next to "that," so it's not an error. No need to agonize.

I hope that clears things up!
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My take on option E :

over-fishing and the proliferation of milldams and culverts that have blocked shad migrations up their spawning streams had reduced landings to less than four million pounds

(E) having blocked shad migrations up their spawning streams had reduced landings to an amount lower

Reason for eliminating option E :

Modifier 'having blocked shad migrations' applies to 'mildams and culverts' but since this noun is itself modifying the noun 'proliferation', it is safe to say that 'having blocked shad migrations' refers to 'proliferation' .
Now the 2nd part 'had reduced' can't refer to proliferation, because if it did then the 1st half ('overfishing')of the subject ('over-fishing and the proliferation') will be without a verb. So it is safe to say that 'had reduced' refers to overfishing and proliferation.

Now since the above part is clear :
We can clearly see that the 2nd part of the subject with its modifier will not make sense by itself :
proliferation of mildams and culverts having blocked shad migrations up their spawning streams
what did they do after having blocked it ???
"Having + past participle" is called a perfect participle - it is used to depict an action that has been completed before another action. So in this case what is the other action ?? xD)

So now we can clearly eliminate option E on strong grounds

Applying similar logic to option B -> its clearly the correct answer without a doubt.

Hello experts; MartyTargetTestPrep egmat GMATNinja

Can you please explain the uses of Less ve Lower in general?
I've seen it appeared many times in Og questions!

I've seen many post regarding this, all of them are saying different things, I would like to have an expert opinion!
please provide the simplest way to remember this with examples
Thanks!

I wouldn't try to generalize here. Off the top of my head, you could have:

- Company A has lower costs than company B.
- Company A uses less energy than company B.
- Tim's energy level is lower than Dan's.
- Eight is less than nine.
- If your company is valued at eight dollars, it has a lower valuation than Tim's company, which is worth nine dollars.
- If your company is valued at more than eight dollars, you have less to worry about.

Anything to generalize there? Debatable, but I wouldn't waste any brain space memorizing scenarios. Instead I'd either use context to evaluate the logic of the usage or move on to other issues you feel more confident about.

I hope that helps a bit!
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GMATNinja

Can you please explain how "that" can be used to refer to "over-fishing and the proliferation of milldams and culverts"?

Context! As soon as I see "that" as a modifier, the first thing I'll do is check out the associated verb to see if it offers any insight about whether "that" is describing a singular or plural noun. Here, I have "blocked," so that's not too helpful -- I could write "it blocked" or "they blocked."

Next, I'll use the logic of the modifier itself. Here, we have "that blocked shad from migrating." Okay, now my eyes shift to the left, in search of a noun or noun phrase that might have blocked these poor shad.

Could the mildams and culverts have done it? Sure. Could it have been the "proliferation" of these mildams and culverts? Yep. What's important is that it makes perfect sense for mildams and culverts to block fish. No need to waste any energy splitting hairs here -- there's a noun or noun phrase that could be modified logically by "that," so I know it's not a concrete error, and I can move on to other issues. Simple as that.

I hope that helps!
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GMATNinja
Thanks for the nice explanation.
I'm just unable to digest the highlighted part! Can you clarify a little bit, please?
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Around 1900, fishermen in the Chesapeake Bay area landed more than seventeen million pounds of shad in a single year, but by 1920, over-fishing and the proliferation of milldams and culverts that have blocked shad migrations up their spawning streams had reduced landings to less than four million pounds.


(A) that have blocked shad migrations up their spawning streams had reduced landings to less

(B) that blocked shad from migrating up their spawning streams had reduced landings to less

(C) that blocked shad from migrating up their spawning streams reduced landings to a lower amount

(D) having blocked shad from migrating up their spawning streams reduced landings to less

(E) having blocked shad migrations up their spawning streams had reduced landings to an amount lower
Hi experts,

Which one blocked shad migrations up their spawning streams? Is it ''over-fishing and the proliferation of milldams and culverts'' or ''milldams and culverts''?
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GMATNinja
if the ''proliferation'' itself can block then the ''over-fishing'' can also block shad as ''proliferation'' and ''over-fishing'' have been added by the word 'and', right?
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