New techniques in thermal-scanning photography, a process that records

Dear Friends,

Here is a detailed explanation to this question-

Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended core meaning of the sentence is that new techniques in thermal-scanning photography have made it possible to study the effects of the calefaction of a river in greater detail than ever before.

Concepts tested here: Subject-verb Agreement + Meaning + Tenses + Verb Forms + Redundancy/Awkwardness

• The present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present.
• The simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.
• The infinitive verb form (“to + base form of verb"- "to + study" in this sentence) is the preferred construction for referring to the purpose/intent of an action.

A: This answer choice incorrectly uses the singular verb “makes” to refer to the plural noun “techniques”. Further, this answer choice incorrectly uses the simple present tense verb "makes" to refer to an action that happened in past but continues to affect the present; please remember, the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present, and the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.

B: Trap. This answer choice incorrectly uses “than ever before” to modify “calefaction...of a river" rather than “in greater detail”, leading to an incoherent meaning; the intended meaning of the sentence is the new techniques in thermal-scanning photography have made it possible to study the effects of the calefaction of a river in greater detail than ever before. Further, Option B incorrectly uses the simple present tense verb "makes" to refer to an action that happened in past but continues to affect the present; please remember, the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present, and the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.

C: Correct. This answer choice correctly uses the plural verb “have made” to refer to the plural noun “techniques. Further, Option C correctly uses “than ever before” to modify “in greater detail”, conveying the intended meaning - that the new techniques in thermal-scanning photography have made it possible to study the effects of the calefaction of a river in greater detail than ever before. Additionally, Option C correctly uses the present perfect tense verb “have made” for an action that happened in past but continues to affect the present. Option C also uses the infinitive verb form (“to + base form of verb” – “to + study” in this sentence) to refer to the intent of the action “have made it possible”. Besides, Option C is free of awkwardness and redundancy.

D: This answer choice incorrectly uses the simple present tense verb "makes" to refer to an action that happened in past but continues to affect the present; please remember, the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present, and the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature. Further, Option D uses the noun phrase “the study of the effects of calefaction” to refer to the intent of the action “make possible”; please remember, the infinitive verb form (“to + base form of verb") is the preferred construction for referring to the purpose/intent of an action. Besides, Option D uses the needlessly wordy phrase “make possible the study of the effects of calefaction”, leading to awkwardness and redundancy.

E: This answer choice incorrectly uses the singular verb “has made” to refer to the plural noun “techniques”. Additionally, the phrase “more possible than ever before to study in greater detail the effects of calefaction” is needlessly wordy, leading to awkwardness in this answer choice.

Hence, C is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~2 minutes):



To understand the concept of "Present Perfect Tense" on GMAT, you may want to watch the following video (~1 minute):



All the best!
Experts' Global Team

IMO C

(A) makes it possible to study the effects of calefaction, or warming, of a river in greater detail than ever before (Techniques - should be make)
(B) make it possible to study, in greater detail, the effects of calefaction, or warming, of a river than ever before (in greater detail is wrongly placed)
(C) have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river ---- Correct
(D) make possible the study of the effects of calefaction, or warming, of a river in greater detail than it ever was before (make possible the study is wrong)
(E) has made it more possible than ever before to study in greater detail the effects of calefaction, or warming, of a river ---- (Techniques ----should be have)

Can anybody explain that why is option B not correct and C is the answer.

can you guys please clarify as to what does "IT" refers to in option C.

have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river

Here the "it" is used as a pronoun to anticipate "the effects..."

"have made the effects of (...) possible to study in greater detail..."

The pronoun is introduced before the antecedent.

eg. I love it when the sky is clear.
or, Your abstruse approach makes it difficult to understand the solution.

We are describing the antecedent using a pronoun modifier. This is perfectly acceptable.

New techniques in thermal-scanning photography, a process that records radiation from surface areas, makes it possible to study
the effects of calefaction, or warming, of a river in greater detail than ever before.
(A) makes it possible to study the effects of calefaction, or warming, of a river in greater detail than ever before
phrase "in greater detail than ever before" modifies the verb and should be placed right next to it
(B) make it possible to study, in greater detail, the effects of calefaction, or warming, of a river than ever before
"in greater detail than ever before" should not be separated. Otherwise, we need another subject and a verb to make it work.
(C) have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river. Correct
(D) make possible the study of the effects of calefaction, or warming, of a river in greater detail than it ever was before. They key here, I believe, "the study in greater detail" is inferior to "to study in greater detail. A study that is more detailed than ever before would have made D more attractive than it is now.\

(E) has made it possible than ever before to study in greater detail the effects of calefaction, or warming, of a river subject-verb agreement

B) Techniques is a plural term. Obviously it requires a plural verb make.

C) Now the substance of the sentence is that new techniques made it possible in the past, make it possible presently and will make it possible in the future to study in greater detail. The right tense to denote such a day-to-day affair is the use of simple present. Hence make it possible rather than have made it possible.

between B & C,
present perfect makes a better sense, however, apart from tense I can not realize how we can rule out B due to placement of comparative forms of which I'm suspicious.

By rule of grammar, - make it possible - is not ungrammatical although -have made it possible - conveys the meaning of the context better; Secondly the word order in B is erroneous with - than ever before - modifying the warming of a river. It should rightly modify - in greater detail - as in C.

New techniques is a plural subject and demands a plural verb. So, A and E are out.
The problem with D is the ambiguous "IT" at the end because it seems to be referring to something but the meaning is not complete.
Among B and C: Why does in greater detail need to be within commas? Redundancy. Also it seems like in greater detail is not necessary to complete the meaning of the sentence. In other words like a which or a that its a limiting phrase.
Finally if you look at B without the limiting phrase: make it possible to study the effects of calefaction, or warming, of a river than ever before. Does this even make sense? The phrase "than ever before" has to be preceded by the action it modifies which is "in greater detail". So, B is clearly WRONG.

Choose C and move on.

(A) makes it possible to study the effects of calefaction, or warming, of a river in greater detail than ever before
(B) make it possible to study, in greater detail, the effects of calefaction, or warming, of a river than ever before
(C) have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river
(D) make possible the study of the effects of calefaction, or warming, of a river in greater detail than it ever was before
(E) has made it more possible than ever before to study in greater detail the effects of calefaction, or warming, of a river

C is the answer - clear meaning and comparison usage of 'greater...than'

A & E - wrong - because of subject verb
B - wrong because greater ... than are not connected
D-wrong - bad structure - 'make possible ????'

Quite a straightforward one I'd say. Firstly, techniques being the subject requires that the verb be plural. Given this situation, you can eliminate options A and E. Among those that remain:

(D) make possible the study of the effects of calefaction, or warming, of a river in greater detail than it ever was before
Unnecessarily wordy and awkward.

(B) make it possible to study, in greater detail, the effects of calefaction, or warming, of a river than ever before
Awkward construction with the numerous commas.

(C) have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river
Best option. It conveys the point crisply.

New techniques in thermal-scanning photography, a process that records radiation from surface areas , have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river

With (C) for the errors highlighted above...

Well ,I am still not convinced by the OA, and confused between B and C.
Yes, I agree that have does appear nice.
BUT as per my knowledge in GMAT it is preferred to use Simple tense as much as possible unless the sentence is not grammatically wrong AND perfect tenses are generally not used.
Can anybody please correct me..??

suramya26



I am afraid you are wrong to a very great extent. If you go with such notions into the exam, you will end up only getting the short end of the stick.
There are three simple tenses in grammar. i.e. a simple past, a simple present, and a simple future. It is not clear which one you are referring to.
The right perspective is that one should use the correct tense as the context demands. I do not think there is any preference, said either explicitly or implicitly by GMAT in the choice of the tense.
It must also be noted that most of the higher level questions involve the use of past and present perfect tenses or the use of the third conditionals in GMAT

Thanks a lot sir,
Sir , the tell me whether my reasoning is wrong??
The reason for which C is the correct answer is because the option stresses on the effect of new technologies
And this the effect is still IN THE PRESENT

Suramya

Hi

Don’t you feel that there is no difference between B and C as far as new techniques are concerned? C is better because of the superior word order; in B, the placement of ‘than ever before’ after the river is changing the meaning.