Perhaps I can help clarify the trouble people are having with past perfect ("had been") vs. simple past ("was").

First, past tense does not necessarily mean that something is no longer true. For instance, I might say "When I was a child, I wanted to grow up fast because my brother was so much older than me." This doesn't mean that my brother is no longer older (thankfully, I still have my brother!). I am just talking about him in a past context. It would be wrong in this case to say "is so much older" just because he is still older.

Second, we don't always need to use past perfect when we have more than one past event. We only use it when the order of those events needs to be clarified or emphasized. For instance, we would say "I was born and raised in California," and not "I had been born in California and then raised there." It's clear enough that being born came first, so there's no need to use the past perfect to clarify. In other cases, we simply don't care which came first. If I say "I have studied French, Spanish, and Russian," I don't need to use "had" to show which came first unless the order is somehow important: "I had already studied French when I started to learn Spanish, so I had an easier time learning vocabulary."

Third, if we are going to use past perfect, we must have a clear time in the past that we are placing our action before. If I say "X had happened," I need to say which past event it preceded, or at what point in the past it had already happened: "X had happened when Y came along" or "By 1850, X, Y, and Z had happened." I was initially going to use "X had happened before Y did," but that's a case that's clear enough without past perfect, so it would be better to use simple past: "X happened before Y did." Notice that dropping "had" from my earlier examples reduces their clarity: "X happened when Y came along." (At the same time? After?) "By 1850, X, Y, and Z happened." (This is not as bad, but it makes it a little less clear that all of these things could have happened at any time before 1850, perhaps even many years earlier.)

Regarding this usage in particular, notice that E doesn't provide any reason to use past perfect. The most simple way to see this is that although we have more than one point in time (the 18th c. and 25 years ago), the main core of sentence does not say that leaching was a method before or by one of those times (the modifier does, but it's not part of the action!). It just says "Leaching had been a method, but until 25 years ago," we didn't know a certain thing about it. When I see "had been a method," I immediately want to know "until what?" The sentence doesn't answer that. On the contrary, it makes it seem that leaching continues--we just know more about it now. Furthermore, even if people stopped using this method, it would still be a method of mineral extraction--it just wouldn't remain in use.

Consider this case:

"Cockroaches had been an insect, but last year, scientists learned more about them." What? Cockroaches had been an insect? Did they stop being an insect and turn into something else? When did this happen? This sentence doesn't make much sense meaning-wise, but it also doesn't meet the criteria for past perfect. We aren't situating one past event in relation to another.

When would "had" be appropriate? Try this:

"By the time the first birds evolved, cockroaches had already been flying for millions of years."
_________________

Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago, miners did not realize that bacteria take an active part in the process.

A. as a method of the extraction of minerals, it was well established ---'leaching and it' makes it an error of double subjecting with a single verb
B. as a method of the extraction of minerals well established -- This is a fragment.
C. was a well-established method of mineral extraction ---correct choice
D. was a well-established method of extracting mineral that was ---that refers to mineral and not to extracting mineral
E. had been a method of mineral extraction, well established -- if leaching had been a well-established method as early as 18th century, what happened to the method after the specified timeline? 'Had been' can be used only if the method ceased to be well established after the 18th century.
_________________

C it is
A and B miss verb to make first half a clause
D) "that was as early as" is not english
E) misplaced modifier problem. Is it the "mineral extraction" or the "method which is "well-established"?

C) has correct verb-tense agreement and makes "well-established" adjective of proper noun "method"

A. as a method of the extraction of minerals, it was well established
"it" is wrong
B. as a method of the extraction of minerals well established
missing a verb
C. was a well-established method of mineral extraction
sounds good
D. was a well-established method of extracting mineral that was
Sounds like the mineral was as early as 18 century
E. had been a method of mineral extraction, well established
The comma before "well" is wrong.

I would choose (C) for this one.

Refer the below site to understand the usage of 'had been':

http://www.englishpage.com/verbpage/pas ... nuous.html

IMO:

When we use had been in this sentence it would mean L is a method established in the past and not in use anymore. But the sentence is not trying to make that meaning.

Thanks,
A

Option A - Incorrect.

Remove the modifier in the middle - "the recovery of copper from the drainage of mines".

We get the sentence -

"Leaching, as a method of the extraction of minerals, it was well established ..." - Incorrect.

this is like saying "John, he went to the movies". the subject "leaching" is repeated again as "it". Hence, redundant.

Option B - Incorrect.
Remove the modifier in the middle - "the recovery of copper from the drainage of mines".

"Leaching as a method of the extraction of minerals well established as early as 18th century, but until about 25 years ago miners did not realize that bacteria take an active part in the process."

Note that "but" requires parallelism. the right hand side "miners did not realize ..." is a complete clause.
However, the left hand side "leaching as a method ..." is not.

Option C - Correct answer.

Option D - Incorrect.
"Leaching was a well-established method of extracting mineral that was as early as the eighteenth century" --->
"method that was early as 18th century" - Incorrect. "Method" cannot be as early as 18th century. (we are comparing "method" to "18th century"). We need to say that the method was discovered as early as 18th century.
(Option C says "leaching was well-established as early as 18th century").

Option E - incorrect.
"Leaching had been a method of mineral extraction" - Usage of "had been" is not required.
_________________

please tell me why we eliminated a and b and e and why we went with was form?

Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.

(A) as a method of the extraction of minerals, it was well established
verb is missing , therefore Incorrect

(B) as a method of the extraction of minerals well established
verb is missing , therefore Incorrect

(C) was a well-established method of mineral extraction
No error

(D) was a well-established method of extracting mineral that was
Illogical meaning . that is modifying mineral.

(E) had been a method of mineral extraction, well established
what is well established is modifying here ( noun modifier should be placed as close as possible to noun it is modifying) . There is no need to use past perfect as the temporal relationship is explicitly indicated and no separate emphasis is required.

Here is the sentence structure of this sentence:
Clause 1: Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals,
Clause 2: it was well established as early as the eighteenth century,
Clause 3: but until about 25 years ago miners did not realize
Clause 4: that bacteria took an active part in the process.

Clause 1 does not have any verb. The subject “leaching” does not have any verb. Thus this sentence is a fragment. In addition, clause 2 is not connected appropriately to clause 1. It should be connected using a ; or ,FANBOYS.


Process of Elimination :-

Choice A - 'leaching and it' makes it an error of double subjecting with a single verb
Choice B – Fragment Error: This choice changes clause 2 into a modifier. But it does not address the absence of verb for the subject “leaching”.
Choice C – No errors.
Choice D – Modifier error: The sentence implies that well-established method of mineral extraction was as early as 18th century. This is non-sensical – saying that a method was as early as 18th century. It would have made sense if this said that the method existed as early as 18th century. This error may be construed as SV-Make sense error – the subject – “well established method” does not make sense with the verb – “was”.
Choice E – Verb error: This choice states uses past perfect tense for the verb – had been. This changes the intended meaning of the sentence. This sentence now implies that leaching is no longer a method of mineral extraction. In the light of this information, what follows does not make sense. Since this is no longer a method of mineral extraction, the fact miners realized its working 25 years back becomes invalid. Thus, because this sentences uses past perfect tense as shown, it distorts the intended meaning of the sentence.
Thus, the correct answer is Choice C.
_________________

Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.

(A) as a method of the extraction of minerals, it was well established - Leaching and it - 2 subjects and one verb
(B) as a method of the extraction of minerals well established - missing verb
(C) was a well-established method of mineral extraction - Correct
(D) was a well-established method of extracting mineral that was - illogical - leaching was not as early as the eighteenth century
(E) had been a method of mineral extraction, well established - tense issue - if the past perfect is used to describe a state or description of something (as opposed to an action verb), it should generally be used to describe a state/description that is no longer the case. since leaching is presumably still an extraction method (this is not the sort of thing that is subject to change), the past perfect is inappropriate.

Also, the modifier (starting with "well established") shouldn't be a nonessential modifier, i.e., it shouldn't be set off by commas.

Answer C
_________________

look at choice B
establish need a object and can not stand without object. it is transitive verb.

that is why choice B is wrong.

am i correct ?

Dear sir , will this be a correct sentence ?

Leaching, the recovery of copper from the drainage water of mines, is a well established method of the extraction of minerals as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.

Hello Bunuel

Kindly underline the question... Thanks
_________________

________________________
Done. Thank you.
_________________

A. as a method of the extraction of minerals, it was well established
B. as a method of the extraction of minerals well established (fragment)
C. was a well-established method of mineral extraction
D. was a well-established method of extracting mineral that was
E. had been a method of mineral extraction, well established

thank you Dmitry for explanation of 'had done".
I just want to say some words more.

if the context makes it clear that one action precede or finished before another action, we dont use past perfect but use 2 simple past tenses.

he was born speaking Vietnamese, but he mastered english.

but if context is unclear in that context could offer 2 meanings- two actions happen simultaneously and two actions are in sequence-, the we have to past perfect to show a specific meaning. if we dont use past perfect, the second meaning happens.
from this point, the effective way to test whether past perfect is correct is to replace past perfect with simple past. if this replacement change meaning, the past perfect is correct.

when you came, I had had my lunch
when you came, I had my lunch

so, we have the hard situation. for the same meaning- one action finished before the other-, we still have to use 2 patterns: simple past+simple past and past perfect+simple past.

when you came, I had had my lunch
he was born speaking vietnamese, but he mastered english.

both sentence show that one action precedes the other, but one sentence use past perfect+ simple past and the other uses simple past+simple past.

in other words, there are 2 ways to show one action precedes the other
1. clear context
2. had done

we dont use past perfect when
1. sequence /context is clear
2, we dont care which action come first.
we use past perfect when
we want to emphasize sequence and context is unclear

pls, comment on my explanation. I could come back to revise it

thangvietnam Two problems with that:

1) In this context, "established" isn't a verb. It is a past participle modifying "method": the method was well-established by the 18th century.

2) Even if we had a proper verb, it is part of a larger modifier ("as a method . . . century"), so it can't be the main verb. Consider this flawed example:

My parents, who arrived early, but didn't get tickets.

In this case, "arrived" is definitely a verb, but it is part of a modifier adding detail about my parents. It is not part of the sentence core. If we take the modifier out, we have "My parents, but didn't get tickets." This is clearly not a proper sentence, even though it has an additional verb ("get"). We need an action before "but" to justify that conjunction! To fix it, I can just cut "who" and the comma:

My parents arrived early but didn't get tickets.
_________________

While I do understand why the other choices are wrong. I also feel the Choice "C" is a bit awkward. Shouldn't there be a preposition post extraction connecting with the second part of the sentence? It currently reads-Leaching, xxx, was a well-established method of mineral extraction(without a preposition) as early as the 18th ........?

That usage is okay. In case it helps, here are a few more examples:

1. The extinction event was thought to have occurred as many as ten million years ago.
2. The website was compromised as early as January 2014.
3. He was considered the most successful player in the league as early as 2016.
_________________