GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 17 Feb 2019, 13:03

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

## Events & Promotions

###### Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• ### Free GMAT Algebra Webinar

February 17, 2019

February 17, 2019

07:00 AM PST

09:00 AM PST

Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT.
• ### Valentine's day SALE is on! 25% off.

February 18, 2019

February 18, 2019

10:00 PM PST

11:00 PM PST

We don’t care what your relationship status this year - we love you just the way you are. AND we want you to crush the GMAT!

# The westinghouse air brake, first demonstrated successfully in 1868, h

Author Message
TAGS:

### Hide Tags

Intern
Joined: 30 Aug 2015
Posts: 24
GMAT 1: 570 Q47 V23
GMAT 2: 570 Q42 V27
GMAT 3: 680 Q50 V35
The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

29 Apr 2016, 06:59
6
28
00:00

Difficulty:

35% (medium)

Question Stats:

69% (01:28) correct 31% (01:40) wrong based on 1099 sessions

### HideShow timer Statistics

The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

29 Apr 2016, 14:45
9
7
inakihernandez wrote:
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.

Dear inakihernandez,

My friend, I'm happy to respond.

Official GMAT SC questions are funny. Many times, the OA is a well-written gem, beautifully crafted, but sometimes the OA still has issues but it's the best of the bunch. I think this is such a question.

The opening "whereas" is a much more natural way to create the contrast that the writer is trying to create. The word "whereas" suggests contrast but it also implies a comparison, whereas the word "but" simply delineates a sharp change in the direction of the logic.

Choice (A) uses "they" to refer to the trains and then says "such a train"---this double reference is confusing.

Choice (B) has no pronoun issues, and it uses the "whereas," so it's best of this bunch. This is a rare official GMAT SC question in which I am embarrassed by the poor quality of the OA. It sounds as if the "5 hand breakers" are physically separated from one another over a distance of 1500 meet---that, of course, is not the intended meaning, but that's how it sounds. This entire sentence would have to be re-written to create complete clarity. So, this is a very-far-from-ideal question, but (B) stands out as head and shoulders above the rest, so in that sense, this question has a very clear answer.

Does this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

##### General Discussion
SC Moderator
Joined: 13 Apr 2015
Posts: 1687
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

29 Apr 2016, 19:25
1
Hi mikemcgarry,

Can you please check my reasoning given below. In addition to your comments, is it safe to consider a 3-2 split in the answer choice based on the usage of 'before' and 'previously'. Once the splits are identified the answer can easily be narrowed down to B because of pronoun error in D.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped. - Incorrect - 'they' incorrectly refers to freight cars. Also 'before' does not correctly point to the time frame in discussion.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train. - Correct - 'previously' correctly refers to the timeframe between 1868 - 1887. Since 'previously' is used there is no need to use past perfect. But there is no real harm in using past perfect here. Also the non underlined part contains had been, indicating the development of brakes from 1868 - 1887. So, the usage of had been seems appropriate here to cover the entire timeframe.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet. - Incorrect - before does not clearly point to the timeframe in discussion.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train. - Incorrect - Pronoun error

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet. - Incorrect - Same error as option C.

Thanks
Senior Manager
Joined: 02 Dec 2014
Posts: 368
Location: Russian Federation
Concentration: General Management, Economics
GMAT 1: 640 Q44 V33
WE: Sales (Telecommunications)
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

30 Apr 2016, 14:34
I think we can use past perfect in B since an action started and finished in the past
_________________

"Are you gangsters?" - "No we are Russians!"

Manager
Joined: 07 Dec 2009
Posts: 91
GMAT Date: 12-03-2014
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

01 May 2016, 00:38
Ans : B

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped. - what does 'they' refer to ?

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train. (Looks ok)

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet. - Sounds as if 'something' was taking place before stopping the train

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train. - Same as A

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet. - Sentence doesn't make much sense
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

02 May 2016, 10:14
3
Vyshak wrote:
Hi mikemcgarry,

Can you please check my reasoning given below. In addition to your comments, is it safe to consider a 3-2 split in the answer choice based on the usage of 'before' and 'previously'. Once the splits are identified the answer can easily be narrowed down to B because of pronoun error in D.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped. - Incorrect - 'they' incorrectly refers to freight cars. Also 'before' does not correctly point to the time frame in discussion.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train. - Correct - 'previously' correctly refers to the timeframe between 1868 - 1887. Since 'previously' is used there is no need to use past perfect. But there is no real harm in using past perfect here. Also the non underlined part contains had been, indicating the development of brakes from 1868 - 1887. So, the usage of had been seems appropriate here to cover the entire timeframe.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet. - Incorrect - before does not clearly point to the timeframe in discussion.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train. - Incorrect - Pronoun error

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet. - Incorrect - Same error as option C.

Thanks

Dear Vyshak,
I'm happy to respond. My friend, I have no complaint about your logic. The past perfect in (B) is fine. I still maintain that there is something fundamentally illogical about their placement of the adverbial phrase "over a distance of 1,500 feet." I believe what the sentence means to imply is a direct comparison to the 171 feet in the first part: in other words, this is suppose to indicate what the stopping distance of the train was under the previous breaking system. Instead, they way it is currently positions in all the choices including the OA, it sounds as if it indicates where the 5 hand breakers had been standing. It's a very poor and illogical question.

My friend, your logic is fine, but the question is flawed.

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Intern
Joined: 21 Oct 2015
Posts: 46
GMAT 1: 620 Q47 V28
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

15 May 2016, 19:33
mikemcgarry wrote:
inakihernandez wrote:
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.

Dear inakihernandez,

My friend, I'm happy to respond.

Official GMAT SC questions are funny. Many times, the OA is a well-written gem, beautifully crafted, but sometimes the OA still has issues but it's the best of the bunch. I think this is such a question.

The opening "whereas" is a much more natural way to create the contrast that the writer is trying to create. The word "whereas" suggests contrast but it also implies a comparison, whereas the word "but" simply delineates a sharp change in the direction of the logic.

Choice (A) uses "they" to refer to the trains and then says "such a train"---this double reference is confusing.

Choice (B) has no pronoun issues, and it uses the "whereas," so it's best of this bunch. This is a rare official GMAT SC question in which I am embarrassed by the poor quality of the OA. It sounds as if the "5 hand breakers" are physically separated from one another over a distance of 1500 meet---that, of course, is not the intended meaning, but that's how it sounds. This entire sentence would have to be re-written to create complete clarity. So, this is a very-far-from-ideal question, but (B) stands out as head and shoulders above the rest, so in that sense, this question has a very clear answer.

Does this make sense?
Mike

Hi Mike,

Thanks for your explanation. I chose wrong option on practice test for the following reasons :

1. I couldn't split between 'whereas' and 'but'. I ignored because both show contrast to some extent. There are other officials problems in which the ans choices are split between words (or conjuctions) which convey the same meaning but may not fit in given context for one or other reason. Any safer approach to avoid such traps?

2. I rejected B because I couldn't rationalise whether past perfect is ok. If the question stem (Without dates/timeframes) demands sequencing of events in past, I still do better. But it gets tougher when the stem involves years/dates etc. I was confused for the same reason.

3. Before/previously - same reasons as 1.

Only thing I could properly use was - pronoun agreement which helped me to reject two choices at best.

Cheers
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

16 May 2016, 10:44
6
4
HarisinghKhedar wrote:
Hi Mike,

Thanks for your explanation. I chose wrong option on practice test for the following reasons :

1. I couldn't split between 'whereas' and 'but'. I ignored because both show contrast to some extent. There are other officials problems in which the ans choices are split between words (or conjuctions) which convey the same meaning but may not fit in given context for one or other reason. Any safer approach to avoid such traps?

2. I rejected B because I couldn't rationalise whether past perfect is ok. If the question stem (Without dates/timeframes) demands sequencing of events in past, I still do better. But it gets tougher when the stem involves years/dates etc. I was confused for the same reason.

3. Before/previously - same reasons as 1.

Only thing I could properly use was - pronoun agreement which helped me to reject two choices at best.

Cheers

Dear HarisinghKhedar,
I'm happy to respond. I will go through your numbers in reverse order.

3) On "before" vs. "previously," notice a subtle difference. The word "previously' is 100% an adverb and nothing but an adverb: its usage is perfectly unambiguous. By contrast, the word "before" can be used either as an adverb (as it is used in these answer choices in this problem) or as a subordinate conjunction or as a preposition.
He came to the house to visit me, but before, I had left to go to the store. = adverb use of "before"
Before he came to the house to visit me, I already had left to go to the store. = subordinate conjunction use of "before"
Before his arrival at the house looking for me, I already had left to go to the store = preposition use of "before"
In this problem, the word "before" is intended in its adverb usage, but it creates ambiguity because it could be understood as preposition:
(C) ... but, before stopping the train, [who?] required 5 hand breakers operating over a distance of 1,500 feet
That opening phrase "before stopping the train" is likely to be understood as a prepositional phrase, and when we get to the verb, we realize, "wait, we need a subject!" We have to go back and re-interpret the word "before" as a adverb and the gerund "stopping" as the subject. This is a very subtle point. Any piece of writing that creates the expectation of one sort of reading and then jarringly forces us to adapt another reading is rhetorically awkward. Good writing fulfills our grammatical expectations in a way that allows the meaning to unfold. That's a problem with "before" in this context.

2) For use of the past perfect, see this blog:
Past Perfect on GMAT Sentence Correction
You will notice that in the example sentence in #3, I used the past perfect, even though there were other indicators of the time sequence. I did so because I was trying to create emphasis: this is a justifiable use of the past perfect even when other elements of the sentence indicate the time sequence. Much in the same way, the sentence in this official SC question is creating this huge sense of contrast between after the air brake vs. before the air brake. The past perfect helps to underscore that logical and rhetorical contrast.

1) This is the hardest, especially for folks for whom English is not a native language---the subtle differences between closely related words. Here, "but" and "whereas" are both contrast words: that is there similarity. The difference lies in the connotation, the quality of the contrast. The word "but" is a 180-degree completely turn around. The word "whereas" is softer, suggesting comparison and connection as well as contrast. I don't know if you have an experience with improv theater: the word "but" is many ways is equivalent to a kind of "no," whereas the word "whereas" is more equivalent to "yes and" (in improv theaters, actors are told to avoid the word "but" and make use of "yes and," to keep the flow of the dialogue going).

How do you learn all these subtle distinctions and connotations? By reading. See:
How to Improve Your GMAT Verbal Score
It is impossible to arrive at GMAT SC mastery by assembling some complete list of differences in meaning. That is a left-brain fantasy that is entirely unworkable. The only way to develop the intuition for the language is to develop a rigorous habit of daily reading.

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Intern
Joined: 21 Oct 2015
Posts: 46
GMAT 1: 620 Q47 V28
The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

17 May 2016, 01:01
mikemcgarry wrote:
HarisinghKhedar wrote:
Hi Mike,

Thanks for your explanation. I chose wrong option on practice test for the following reasons :

1. I couldn't split between 'whereas' and 'but'. I ignored because both show contrast to some extent. There are other officials problems in which the ans choices are split between words (or conjuctions) which convey the same meaning but may not fit in given context for one or other reason. Any safer approach to avoid such traps?

2. I rejected B because I couldn't rationalise whether past perfect is ok. If the question stem (Without dates/timeframes) demands sequencing of events in past, I still do better. But it gets tougher when the stem involves years/dates etc. I was confused for the same reason.

3. Before/previously - same reasons as 1.

Only thing I could properly use was - pronoun agreement which helped me to reject two choices at best.

Cheers

Dear HarisinghKhedar,
I'm happy to respond. I will go through your numbers in reverse order.

3) On "before" vs. "previously," notice a subtle difference. The word "previously' is 100% an adverb and nothing but an adverb: its usage is perfectly unambiguous. By contrast, the word "before" can be used either as an adverb (as it is used in these answer choices in this problem) or as a subordinate conjunction or as a preposition.
He came to the house to visit me, but before, I had left to go to the store. = adverb use of "before"
Before he came to the house to visit me, I already had left to go to the store. = subordinate conjunction use of "before"
Before his arrival at the house looking for me, I already had left to go to the store = preposition use of "before"
In this problem, the word "before" is intended in its adverb usage, but it creates ambiguity because it could be understood as preposition:
(C) ... but, before stopping the train, [who?] required 5 hand breakers operating over a distance of 1,500 feet
That opening phrase "before stopping the train" is likely to be understood as a prepositional phrase, and when we get to the verb, we realize, "wait, we need a subject!" We have to go back and re-interpret the word "before" as a adverb and the gerund "stopping" as the subject. This is a very subtle point. Any piece of writing that creates the expectation of one sort of reading and then jarringly forces us to adapt another reading is rhetorically awkward. Good writing fulfills our grammatical expectations in a way that allows the meaning to unfold. That's a problem with "before" in this context.

2) For use of the past perfect, see this blog:
Past Perfect on GMAT Sentence Correction
You will notice that in the example sentence in #3, I used the past perfect, even though there were other indicators of the time sequence. I did so because I was trying to create emphasis: this is a justifiable use of the past perfect even when other elements of the sentence indicate the time sequence. Much in the same way, the sentence in this official SC question is creating this huge sense of contrast between after the air brake vs. before the air brake. The past perfect helps to underscore that logical and rhetorical contrast.

1) This is the hardest, especially for folks for whom English is not a native language---the subtle differences between closely related words. Here, "but" and "whereas" are both contrast words: that is there similarity. The difference lies in the connotation, the quality of the contrast. The word "but" is a 180-degree completely turn around. The word "whereas" is softer, suggesting comparison and connection as well as contrast. I don't know if you have an experience with improv theater: the word "but" is many ways is equivalent to a kind of "no," whereas the word "whereas" is more equivalent to "yes and" (in improv theaters, actors are told to avoid the word "but" and make use of "yes and," to keep the flow of the dialogue going).

How do you learn all these subtle distinctions and connotations? By reading. See:
How to Improve Your GMAT Verbal Score
It is impossible to arrive at GMAT SC mastery by assembling some complete list of differences in meaning. That is a left-brain fantasy that is entirely unworkable. The only way to develop the intuition for the language is to develop a rigorous habit of daily reading.

Does all this make sense?
Mike

Hi Mike,
Thanks a lot for the entire content. It was very helping and insightful.

I would also like to know your opinion on cases which are recommended not preferable on GMAT. Cases like below:

Usage of 'being'
Usage of '[PREPOSITION]+[NOUN]+[VERBing]'
Usage of 'Past perfect' when sequence is clear - our case

All these cases among similar others are not outright wrong but less likely to be correct. They may fit well given other choices are not better. I want to know how should I approach such choices? Should I evaluate the context there and then or skim through other choices first if one fits best? I'm asking this from approach perspective but not a method to minimize my work. Hope you don't misunderstand me in that way. The other day, I spent quality time in figuring out such choices and eventually ended up with lesser than usual accuracy on my sc. Appreciate your help.

Good day!

Posted from my mobile device
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

17 May 2016, 10:38
1
HarisinghKhedar wrote:
Hi Mike,
Thanks a lot for the entire content. It was very helping and insightful.

I would also like to know your opinion on cases which are recommended not preferable on GMAT. Cases like below:

Usage of 'being'
Usage of '[PREPOSITION]+[NOUN]+[VERBing]'
Usage of 'Past perfect' when sequence is clear - our case

All these cases among similar others are not outright wrong but less likely to be correct. They may fit well given other choices are not better. I want to know how should I approach such choices? Should I evaluate the context there and then or skim through other choices first if one fits best? I'm asking this from approach perspective but not a method to minimize my work. Hope you don't misunderstand me in that way. The other day, I spent quality time in figuring out such choices and eventually ended up with lesser than usual accuracy on my sc. Appreciate your help.

Good day!

Dear HarisinghKhedar,
I'm happy to respond.

My friend, it is a difficult thing to understand that there is no such thing as a complete list of the rules of grammar. Many students unconsciously want to treat grammar like mathematics and simply learn all the rules. In math, there are clear black and white rules, and one can learn them. In grammar, there are general patterns, but almost every pattern has an exception. Grammar is an attempt to find patterns in the living and changing language, and it always depends on context and meaning.

1) The word "being" is often wrong, but about 10% of the time, it will appear as a part of a correct answer. It's extremely hard to formulate a general rule for this. It all depends on the individual cases.
2) For the '[PREPOSITION]+[NOUN]+[VERBing]', see this blog article:
with + [noun] + [participle] on GMAT Sentence Correction
BTW, one way to understand grammar better is to learn the proper terminology. The term "VERBing" is extremely sloppy and imprecise, because the -ing form of a verb can have three completely different roles. In this context, the proper word is a participle.
3) As I have already said, this case depends very much on context. As indicated in my response, one reason to use the past perfect in this case is to create contrast and emphasis. When is this appropriate and when would it be too much? This depends on meaning.

Everything on the GMAT SC depends on meaning. Grammar is trumped by meaning. There are no meaningful rules for grammar apart from meaning. This is why it's so important to develop a habit of reading, so you see sophisticated grammatical forms and idioms in context. There is no substitution for that.

It's almost impossible to discuss some of these topics in the abstract, as if they were mathematics. We have to look at individual sentences. I will ask you to find, posted here already on GMAT Club, sentences that have confused you. In that thread, make an entry and use the "mention this user" button to solicit my input. It's only by looking a specific sentences that we can address these issues properly.

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Intern
Joined: 21 Oct 2015
Posts: 46
GMAT 1: 620 Q47 V28
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

17 May 2016, 23:56
Thank you mikemcgarry. That was very helpful and kind of you.
Intern
Joined: 17 Mar 2015
Posts: 15
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

07 Jul 2016, 22:27
mikemcgarry, I suppose usage of "used to" would have been better instead of "had been"?

"...previously 5 hand breakers used to be required to stop the train..."

The use of past perfect tense is kind of preferable for a one time event, rather than for an ongoing/generic fact/habit/process, right?
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

08 Jul 2016, 12:35
1
TDK82 wrote:
mikemcgarry, I suppose usage of "used to" would have been better instead of "had been"?

"...previously 5 hand breakers used to be required to stop the train..."

The use of past perfect tense is kind of preferable for a one time event, rather than for an ongoing/generic fact/habit/process, right?

Dear TDK82,
I'm happy to respond. Actually, either would be fine in this scenario.

All the past perfect tense logically implies is that the action ended before some other mentioned past event. It is not necessarily limited to a one-and-done, one-time event. It could be something that went on continuously for a considerably long time, as long as it ended before another past event.

Most modern humans are accustomed to a night sky without many stars, even since electric lighting became prevalent in the early 20th centuries, although most humans through history had seen a completely dark sky every single night.

That's an example of an action that continued for over a million years, seeing the completely dark pre-electricity sky, but it ended in the past, so the past perfect is perfectly acceptable. It would also be correct to use "used to see," although that is slightly more casual and not as common in formal writing.

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Senior Manager
Joined: 02 Mar 2012
Posts: 298
Schools: Schulich '16
The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

09 Jul 2016, 03:55
the answer is had been required..this old technique was used before , not now...u need to show this effect.

So B.

Manager
Joined: 29 Oct 2016
Posts: 217
Concentration: Finance, Economics
GMAT 1: 620 Q50 V24
GRE 1: Q167 V147
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

22 Dec 2016, 07:26
Hi mikemcgarry,
Could you please elaborate more on option "E"? I have to admit that the subtle difference between "but" and "whereas" is totally something new to me;however,apart from this preference,is there anything wrong with "E"?
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

24 Dec 2016, 10:41
1
1
sleepynut wrote:
Hi mikemcgarry,
Could you please elaborate more on option "E"? I have to admit that the subtle difference between "but" and "whereas" is totally something new to me;however,apart from this preference,is there anything wrong with "E"?

Dear sleepynut,

I'm happy to respond.

The "but" vs. "whereas" is more a stylistic preference, not a clear issue of right vs. wrong. This would NOT be the basis of split that eliminated an answer.

The BIG problem with (D) & (E) is the ambiguity of the prepositional phrase:
(E) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.

Think about it. Where were these "5 hand brakers"? This phrasing makes it sound as if these five men were standing along the side of the track, spread out 1500 feet from first to last, and somehow they would do something to the train as it went by to stop it. Of course, we realize from the prompt this is not the case, but in (D) & (E) we have "5 hand breakers over a distance of 1,500 feet," so it sounds as if the prepositional phrase is meant to describe the noun, and one obvious conclusion is that the 5 men themselves were spread out over this 1500 feet distance.

The other answers correctly have something along the lines of "5 hand breakers operating over a distance of 1,500 feet." That's completely different. Now, it's 100% clear that the prepositional phrase is not supposed to be an adjectival phrase, a noun modifier; instead, it's supposed to be an adverbial phrase, a verb modifier. That's a huge difference. Now, it's not the men who were spread out over that distance; instead, the activity of operating the brakes and stopping the train took place over that distance. This is the meaning that is consistent with what the prompt is trying to say.

What the sentence is trying to say is that the train itself was much less than 1500 ft long, that the "5 hand brakers" were on the train doing their work, and that when those five men applied the brakes, the train covered 1500 ft of distance in the process of decelerating. In other words, 1500 ft is the "stopping distance" of the train. The "5 hand brakers" might have all been in the same car on the train or might have been spread out over the length of the train, but the action, the action of operating the brakes and stopping, took place over this distance much longer than the length of the train. Choice (B) conveys all this flawlessly.

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Intern
Joined: 04 Jun 2008
Posts: 8
The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

23 Jan 2017, 10:04
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

ambiguous - are they standing 1500 feet apart or operating over a distance of 1500 feet

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.

before stopping the train distorts the meaning, sounds like they have to perform this before stopping the train - They have to do this to stop the train. previously states the correct meaning

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.
Manager
Joined: 26 Mar 2017
Posts: 115
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

23 Jun 2017, 03:34
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped. --> they ?

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet. --> but doesn't make sense imo

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train. --> but doesn't make sense imo

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet. --> but doesn't make sense imo
_________________

I hate long and complicated explanations!

Manager
Joined: 04 Oct 2015
Posts: 241
Location: Viet Nam
Concentration: Finance, Economics
GMAT 1: 730 Q51 V36
GPA: 3.56
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

23 Jul 2017, 18:09
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.

(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.

(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.

(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.
_________________

Do not pray for an easy life, pray for the strength to endure a difficult one - Bruce Lee

Non-Human User
Joined: 01 Oct 2013
Posts: 3632
Re: The westinghouse air brake, first demonstrated successfully in 1868, h  [#permalink]

### Show Tags

08 Sep 2018, 02:54
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: The westinghouse air brake, first demonstrated successfully in 1868, h   [#permalink] 08 Sep 2018, 02:54
Display posts from previous: Sort by