The Chicago and Calumet Rivers originally flowed into the

[ikuta.yamahashi]

oh~
Sorry for my ommit the condition for my concerns...
The MGMAT guide specific this statement at passive voice.

Whoever actually performs the action in the sentence may follow the verb in a phrase headed by the preposition by (by the hungry students). Use by only for the actual doers of the action. Use through or because of when you want to describe any instrument or means, which might be an awkward or nonsensical subject in active voice.

Is this means that in passive voice we can only us by to introduce the agent or the intermediate agent of the action?

Thanks
Yama

Dear instructor:

Two questions for me.
1. According to MGMAT sc guide, "Use by only for the actual doers of the action. Use through or because of when you want to describe any instrument or means, which might be an awkward or nonsensical subject in active voice. "

It confuses me alot, because in your examples above
this result can be found by inspection.
--> correct
inspection is not the doer of the action of discover.
could you help me to slove the paradox?
2. In below sentence from prep, the right choice use by doing/buring/replacing with the subject emissions; however, it seems emission cannot burn or replace anything. I am not intent to challenge the OA, just for confirm the usuage of by doing.

The majority of scientists believe that to reduce and stabilize atmospheric concentrations of carbon dioxide, emissions must be cut at the source by burning fossil fuels more efficiently and, in some cases, by replacing fossil fuels altogether with alternatives such as hydrogen fuel cells
Yama

1. But someone has to be inspecting for the result to be found. Inspection isn't the doer, but the person who is the doer is using inspection. Likewise, "The answer is revealed by pushing a button" The doer in this case is not a button, but the person pushing that button.

2. Same thing in this sentence. The subject is ambiguous (we all have to burn ff more efficiently and replace ff altogether), but it's this ambiguous subject who is doing the action.

I'm not sure where in the SC guide you are reading this difference, but the use of by/through is more of a meaning issue to express whether something is the means or the end. Here's an idiomatic-ly correct illustration of when to use by/through:

We will win the war by force. (force is what will win the war)
We will win the war through diplomacy. (diplomacy will not by itself win the war, but will be a tool we will use to win the war)

Here's some more:
We will win the war...

by bombing their army. (end)
through superior technology. (means)
by capturing their capitol. (end)
through media. (means)

[RonPurewal]

whoa, people

there are two completely different kinds of "by" that are being conflated in the recent posts here.

these are fundamentally different things:

1/
"by" used before the agent of a passive verb
That dress was sewn by Shelly.
The theorem was proved by Andrew Wiles.

2/
"by" used to indicate the method by which something is accomplished
That dress was sewn by hand.
The theorem was proved by induction. (if you don't know, "induction" is a method often used to prove theorems in algebra)

these constructions are completely independent of each other.

#1, of course, requires a passive construction.

#2 doesn't, because #2 has nothing to do with the form of the verb. for instance, you can write That dress was sewn by hand, but you can also write I sewed that dress by hand.

in fact, it's even possible to have both of these constructions in the same sentence:
The theorem was proved by induction by a supercomputer, rather than by a human mathematician.
here, the first "by" is #2, and the second and third are #1.
(you won't see sentences like this often in good writing, because it's generally considered gauche to use the same preposition twice with such proximity; good writers will find some other way to express the same idea. but this sentence is useful in illustrating the two different kinds of "by" described here.)

so, yeah
hope that clears things up. this is not as complicated as it seems.

[ikuta.yamahashi]

Ron Thanks for your reply.

my futher concern on this issue is that both by hand and by induction can be considered as the intermediate agent of the action on your example, because we can say that:
The hand sew the cloth.
and
The induction prove the theorem.
However, can we use by to introduce anything else other than the agent related topic in the passive voice?
For example:
Because of the bad cash flow, the cost was trimmed by 30% of the budget estimation.

Many thanks
Yama

whoa, people

there are two completely different kinds of "by" that are being conflated in the recent posts here.

these are fundamentally different things:

1/
"by" used before the agent of a passive verb
That dress was sewn by Shelly.
The theorem was proved by Andrew Wiles.

2/
"by" used to indicate the method by which something is accomplished
That dress was sewn by hand.
The theorem was proved by induction. (if you don't know, "induction" is a method often used to prove theorems in algebra)

these constructions are completely independent of each other.

#1, of course, requires a passive construction.

#2 doesn't, because #2 has nothing to do with the form of the verb. for instance, you can write That dress was sewn by hand, but you can also write I sewed that dress by hand.

in fact, it's even possible to have both of these constructions in the same sentence:
The theorem was proved by induction by a supercomputer, rather than by a human mathematician.
here, the first "by" is #2, and the second and third are #1.
(you won't see sentences like this often in good writing, because it's generally considered gauche to use the same preposition twice with such proximity; good writers will find some other way to express the same idea. but this sentence is useful in illustrating the two different kinds of "by" described here.)

so, yeah
hope that clears things up. this is not as complicated as it seems.

[tim]

Yes. That is a third use of "by". Ron only mentioned the two that he saw being discussed in the thread, but there are many uses of "by".

[mcmebk]

Hi Instructors

I am interested in knowing if the structure "Clause, but Verbing" would be ever correct.

I finally arrived in the meeting in time, but having been completely annoyed by the traffic congestion.

Would the usage "But+Present Participle" correct here?

Thanks

[RonPurewal]

Hi Instructors

I am interested in knowing if the structure "Clause, but Verbing" would be ever correct.

I finally arrived in the meeting in time, but having been completely annoyed by the traffic congestion.

Would the usage "But+Present Participle" correct here?

Thanks

Sure, you could have that. Most likely, the "-ing" form wouldn't actually be parallel to the whole clause; it would be parallel to some other description.
E.g.,
Walking into the office, James was calm, but breathing heavily.
--> Here, "breathing heavily" is parallel to "calm". Both are descriptions of James (i.e., James was calm, and James was breathing heavily).

--

Disclaimer: I don't know what a "present participle" is, so this example may not address your question.

[eggpain24]

HI,RON

I think I can offer some insight in the correct choice regarding the use of ”flowing“

it adopts the tense from have been redirected

originally flowing → originally have been flowed

what the rivers ”originally flowed“ is still true today (so present perfect is fine)

just correct me If I am wrong

[cherryj222]

The Chicago and Calumet Rivers originally flowed into the St. Lawrence by way of Lake Michigan, but having been redirected by constructing canals so that the water now empties into the Mississippi by way of the Illinois River.
A. Rivers originally flowed into the St. Lawrence by way of Lake Michigan, but having been redirected by constructing
B. Rivers had originally flowed into the St. Lawrence by way of Lake Michigan, but they have been redirected by constructing
C. Rivers, which originally flowed into the St. Lawrence by way of Lake Michigan but have been redirected by the construction of
D. Rivers, originally flowing into the St. Lawrence by way of Lake Michigan, but having been redirected by the construction of
E. Rivers, originally flowing into the St. Lawrence by way of Lake Michigan, have been redirected through the construction of


whats wrong with B..

have been redirected through the construction ??

Hi, experts.
Can you please explain what is wrong with choice A?

[RonPurewal]

Bad parallelism:
flowed (verb)
but
having been... (modifier)

[soulwangh]

Dear instructor:

Two questions for me.
1. According to MGMAT sc guide, "Use by only for the actual doers of the action. Use through or because of when you want to describe any instrument or means, which might be an awkward or nonsensical subject in active voice. "

It confuses me alot, because in your examples above
this result can be found by inspection.
--> correct
inspection is not the doer of the action of discover.
could you help me to slove the paradox?

Hi
I have read all the posts in this thread, but I still have the same questions as this student did.

For the first question:
In MGMAT SC guide 5th, Chapter 7: passive voice, Page 115, the book says "Use by only for the actual doers of the action. Use through or because of when you want to describe any instrument or means, which might be an awkward or nonsensical subject in active voice. "

And it gives some examples:
The Pizza was eaten by a quirk of fate. --->Wrong
A quirk of fate ate the pizza. --->Wrong
Through a quirk of fate, the pizza was eaten--->Right


Ron said in this thread that we can use by + Noun in passive voice sentence, even if the Noun is not the doer of the passive action.
e.g.
this result can be found by inspection.
That dress was sewn by hand.
The theorem was proved by induction.

#Is the book wrong in this part? Please help.

2. In below sentence from prep, the right choice use by doing/buring/replacing with the subject emissions; however, it seems emission cannot burn or replace anything. I am not intent to challenge the OA, just for confirm the usuage of by doing.

The majority of scientists believe that to reduce and stabilize atmospheric concentrations of carbon dioxide, emissions must be cut at the source by burning fossil fuels more efficiently and, in some cases, by replacing fossil fuels altogether with alternatives such as hydrogen fuel cells
Yama

According to the discussion in this thread, I know by doing means the subject is the agent of doing, even in passive voice sentence, except that there is no other dedicated form of doing.
e.g. The money was collected by begging.

#My question is whether the OA sentence quoted above has the same situation that there is no other dedicated form of doing?

If No, why it is the right answer?
After all, Emissions can not be the doer of burning and replacing.

If Yes, I think there should be "the" in front of "burning" and "replacing".
i.e. emissions must be cut by the burning...and by the replacing....
Please judge my reasoning.

Thanks for replying!

[RonPurewal]

that's actually the only sensible way to write that sentence.

"emissions must be cut the more efficient burning" isn't accurate, because the burning doesn't cut emissions. Burning more efficiently is what cuts emissions.

in any case, the GMAT doesn't test subtleties, so the following 2 things are sufficient:

1/
if you're faced with a choice between an __ing form and a dedicated noun form in some context in which the noun form is clearly more appropriate, then choose the noun form.

2/
be aware that both forms are things that exist; do not automatically eliminate "by __ing".

[thanghnvn]

b has only serious error.

had done in b is correct. this is text book case of the usage of past perfect.

[RakshithG27]

Bad parallelism:
flowed (verb)
but
having been... (modifier)

Ron,

Could you please explain the difference between 'Having been + VERBed' and 'Have been + VERBed' with an example.
I am a non native, both look the same to me.

Thanks.

[RonPurewal]

hm... they're completely different things. one is a verb; the other is not.
this is a very, very basic distinction. (without it, you wouldn't even know how to distinguish a sentence from something that isn't a sentence.)

e.g.,
People live in the Arctic.
okay, this is a sentence.

People living in the Arctic...
this is not a sentence; it's just a noun (plus a modifier). you're still waiting for the actual verb (people living in the arctic DO something).

i would bet lots and lots of money that you already understand those ^^ examples.
(if someone doesn't understand those two examples, then, for the moment, (s)he has no business messing around with GMAT SC—that would be like trying to dance if you can't even walk yet. such a person would need to acquire a basic understanding of the structure of written english before returning to the gmat.)

it's the same with those things:
I have been chosen to lead the team.
^^ this is a sentence. etc.

[aflaamM589]

My question is regarding choice E
Rivers, originally flowing into the St. Lawrence by way of Lake Michigan, have been redirected through the construction of canals so that the water now empties into the Mississippi by way of the Illinois River

is usage of flowing(verbing) here correct?
How to justify that it takes the time frame of the main clause, which is have been redirected

To me the meaning is redirection and flowing took place at the same time.
What am i missing here?
Appreciate help.