By the time a way to stop the ozone layer from deteriorating is

By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will be rising for over two hundred years, causing the polar ice caps to gradually melt.


A) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will be rising.
Will be rising does not express correctly the sequence of the events: it looks like in the moment in which the scientists will discover a solution, the deterioration will start. Moreover, the passive form is horrible

B) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will be rising
This adjust the passive form but keep the problem with the verb

C) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures would have been rising
This keep the passive form and presents another problem with the verb. Would have been does not express a sure event, and because we're talking about science, it's not the best way to express it.

D) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will have been rising
Correct one. Adjust the passive form and will have been expresses an event sure in the future that will have continuous effects

E) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will rise
Passive form and verb problem.

D

Would is used when we are not sure of the prediction, will is used for something which will happen in the future, but we are sure about that event
With this in mind, we can eliminate C
C) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures would have been rising

Secondly Intent of the sentence is to show that something which had started in the past, will continue in the future as well.
To show this intent we use Future perfect progressive tense.
Only present in D

A) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will be rising
past tense, present tense - Does not match our intent

B) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will be rising
Not matches the intent

D) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will have been rising
Correct Answer

E) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will rise
Incorrect tense

Man, your images are always so suggestive

OFFICIAL EXPLANATION
coupled with my annotations in blue typeface

• Option A has a grammatically incorrect verb.
Will be rising should be in the [FUTURE] perfect progressive form: will have been rising

• The only answer choice to make this correction also switches from passive voice to active voice, . . .
a switch that is usually preferable.

• Note that choice B also uses the active voice, but B fails to correct the verb error.

The correct answer is D

ANALYSIS
This verb construction is hard.

• NOW → FUTURE, but looking back in time

We are moving ourselves forward in time and looking back at an event that is not finished now, but that will be finished in the future.

Correct: By next summer, he will have been trying to finish the book Ulysses for 12 months. (He started the book last summer.)

Correct: On August 20, 2020, the U.S. space probe Voyager 2 will have been communicating with scientists on Earth for 43 years.

• CUE WORDS
Cue words in this sentence (and often) are
-- "by the time," a phrase that is explained HERE.
-- By the time in this context signals in the future[/i.]

-- Other cue words are [i]for OVER 200 years + CAUSING
Over = more than = a time span, and
causing [ice caps to melt] suggests that the cause, too, is ongoing.

This sentence speaks from the point of view of the present.

The author says that
(1) at some point in the future, scientists will discover a way to stop the ozone layer from deteriorating; BUT
(2) measured from now until that future time at which scientists will make the discovery, the ozone, already deteriorating, will continue to deteriorate

• WILL + HAVE + BEEN + participle (verbING)

If we have an event or action
• that is continuous AND
• that will be completed at some point in the future

we use WILL + HAVE + BEEN + present participle

Jargon: that tense often is called
future perfect progressive or
future perfect continuous
To learn more about this verb construction, see this excellent source, HERE


Right now, the ozone layer IS deteriorating.
Scientists will discover a way to stop this bad event.
But until they do discover a way to stop the bad event, the bad event will keep happening.
WHEN (by the time that) scientists discover a way to stop the bad event, the bad event will have been happening for [a time period of] over 200 years.

This question can be decided on the basis of verb tense alone.

Only option D has the correct verb construction.

• Active voice v. passive voice

My annotations in hot pink suggest that most of the time, active voice is better than passive voice —
but not all of the time.
Please be careful.
This "active voice is always preferred" notion is widely taught.

That notion is not quite accurate.
Go through an official guide or an official verbal review book.
(Or run a strict tag search, HERE and pull all the official questions from one OG, say, 2018, from this site.)

Passive voice is correct in a good number of answers.

All options except D contain incorrect verbs.

Option D's secondary "plus" in this case? It is in active voice. The active/passive choice is contextual.

COMMENTS

These thread topics get better and better.

I see excellent analysis, dialogue (an excellent source of learning plus camaraderie) on this and the thread for today's other question,
creativity [radical understatement], and appreciation of same.

smiley faces = very good answer or +1 for participation
kudos = excellent answers

Nice work, everyone!

By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will be rising for over two hundred years, causing the polar ice caps to gradually melt.

A) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will be rising

B) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will be rising

C) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures would have been rising

D) By the time scientists discover a way to stop the ozone layer from deteriorating, global temperatures will have been rising --> correct

E) By the time a way to stop the ozone layer from deteriorating is discovered by scientists, global temperatures will rise

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