Aerugo, also known as verdigris, is the green "bloom" visible on many

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.
(A)visible on many copper items, and is produced
(B)that is visible on many copper items, and which produces
(C)visible on many copper items, and produces
(D)that is visible on many copper items, and that produces
(E)which is visible on many copper items, and which is produced

Chop the unnecessary clauses:

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.

Aerugo is the green "bloom" visible on many copper items, and is produced over the course of time by the exposure of the metal to the oxygen in the atmosphere.

Clauses like B, D, and E will change meaning.
C is not parallel.
A is best option.

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.

a) visible on many copper items, and is produced

b) that is visible on many copper items, and which produces

c) visible on many copper items, and produces

d) that is visible on many copper items, and that produces

e) which is visible on many copper items, and which is produced
change the intended meaning of the sentence: green "bloom" is not like iron rust, but Aerugo does

asdfghjklasdfghj, this is not an iron-clad rule. We do want to avoid gratuitous commas. For instance, it's wrong to write "I like to sing, and dance." However, there are some cases in which the sentence is potentially complicated or confusing enough that a comma is warranted. There are official GMAT SC questions that do this, even in places where I personally would not choose to use a comma. Here's an example: https://gmatclub.com/forum/covering-71- ... 06346.html

For a detailed explanation of the purpose of the comma in the aerugo sentence, check out Michael Schwartz's comments in our forums:
https://www.manhattanprep.com/gmat/foru ... 10863.html

OFFICIAL EXPLANATION

The original sentence correctly uses the passive construction "is produced," which is necessary because of the later construction "by the exposure of the metal to the oxygen in the atmosphere." Changing this verb to the active voice would create an illogical sentence: "Aerugo...produces...by the exposure of the metal to the oxygen in the atmosphere."

(A) CORRECT. This choice is correct as it repeats the original sentence.

(B) "Produces" is incorrectly in the active voice, making "by the exposure of the metal to the oxygen in the atmosphere" illogical. Moreover, "that" and "which" are unnecessary.

(C) "Produces" is incorrectly in the active voice, making "by the exposure of the metal to the oxygen in the atmosphere" illogical.

(D) "Produces" is incorrectly in the active voice, making "by the exposure of the metal to the oxygen in the atmosphere" illogical. Moreover, both instances of "that" are unnecessary.

(E) "Is produced" is correctly in the passive voice. However, both instances of "which" are unnecessary.

akt715

First, "changes the meaning" is not a correct reason to eliminate an answer. Our job is to find the choice that seems to best convey the author's meaning, and the meaning in A can be incorrect or unclear! Second, there is no difference in meaning, since the sentence tells us that aerugo, verdigris, and the green bloom are all the same thing.

One way to look at E (other than the unsatisfying explanation that "which is not necessary") is that "which" creates a non-essential modifier. If we were going to use a relative pronoun here, we'd want "that," since we are narrowing down the scope of the noun to the bloom that is visible on copper items.

Exactly. We are narrowing down which green bloom we mean with an essential modifier. It's the same as if I said "This is the book needed for the class." I could say "that you need," but either way I'm narrowing down the noun to the specific one I want to talk about.

It is A or E,
E has which, redundant after and,
no clue, confused, SC gurus, help

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.

Because of "by" ==> Passive voice must be used ==> narrow down to A & E.

E is wrong because the structure "Aeguro...... is the green "bloom" which is visible................, and which is produced............." is wrong.

A is correct.

I do not completely understand this question. I have learned that if we have " comma and " we have to have a full sentence with a subject and verb.

Is it possible to use the subject from the other part of the sentence ? If so the rule does not make sense does it ? Because then after the "comma and" I just need a verb


This "rule" that we need after a "comma and" a full sentence is from MGMAT SC Guide



Or do I capture the problem wrong... When I think about it, it seems more like a list of things and not as an Independent sentence... Ok then I guess it ok not to have a subject

It is produced not produces.

Between A and E .

While A shows a complete meaning . E is incomplete sentence. No verb present for the Main subject.

Hence A is right answer.

Though I chose the correct answer, I have a question regarding the usage of 'like usage' here.

1. The part of the sentence after AND is

(Aerugo) is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere. ----> Shouldn't 'like iron rust' touch the subject with which it is compared - we should place like iron rust immediately after the AND?

2. Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and, like iron rust, is produced over the course of time by the exposure of the metal to the oxygen in the atmosphere.
--- in this sentence the part after AND is

(Aerugo) , like iron rust, is produced over the course of time by the exposure of the metal to the oxygen in the atmosphere.

AjiteshArun , GMATNinja , RonPurewal , MagooshExpert , GMATGuruNY , VeritasPrepBrian , MartyMurray , DmitryFarber , daagh , generis , other experts - please enlighten


------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------
Usage of comma + AND for joining 2 clauses- Exception to this rule (from MGMAT forum - https://www.manhattanprep.com/gmat/foru ... 10863.html)

"Standard usage permits a comma here because the first of the two parallel verbs introduces a pretty complicated clause, is the green "bloom" visible on many copper items, whose noun, items, might otherwise seem to be the first of the elements coordinated by and. The comma makes it clear that something earlier in the sentence must be parallel, and when we see that a verb follows and it's not hard to see what that first element is.

I'm not sure that this sentence would be hard to follow without the comma, I'm not sure that it's required, but it is permissible."

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.

I rejected option E because usage of which in the sentence changes the meaning . Because by adding which,the sentence is saying that the green bloom(rather than Aeruog) is produced over the course of time. But in OA explanation they have given some other explanation . Can anyone explain , what is correct reason for rejecting option E?

In this sentence, Aerugo, also known as verdigris, is the green "bloom" visible on many copper items. Here, "visible on many copper items" is a noun phrase modifying "green bloom"? If that's so, shouldn't it be set off by commas as it's a non-essential information?
Eg: The thunderstorm, visible from the seashore, is marching towards the city.
Would it be correct if I were to write- The thunderstorm visible from the seashore is marching towards the city?
Just need a bit more clarity on this. Thank you in advance.

PyjamaScientist

Ah, but the point is that we do not want a non-essential modifier. They are telling us which exact green bloom they are talking about, so the modifier is essential.

What is this though "visible on many copper items"? An essential noun phrase modifier modifying Green bloom?

(A) visible on many copper items, and is produced
THe meaning is spot on therefore let us hang on to it

(B) that is visible on many copper items, and which produces
produces isn't the right usage since the bloom has already occured therefore produced is the right one therefore out

(C) visible on many copper items, and produces
Similar reasoning as B

(D) that is visible on many copper items, and that produces
Similar reasoning as B and use of that in the end isn't having the right reference therefore out

(E) which is visible on many copper items, and which is produced
THis gives us a reasoning as though the coppers are produced like the iron rust which is not the case therefore out

THerefore IMO A

Best way to solve this is to cut the clutter in the sentence
Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.
So basically you have:
Aerugo is the green bloom visible on many copper items
Aerugo is produced like iron rust over the course of time...

So basically is produced is the split you need to look into. So straight up cancel B C and D
E has which - Which is used for unimportant sentences and needs a comma - so eliminate E
Only option A