Dear Friends,
Here is a detailed explanation to this question -
hpmn wrote:
The decline in students' performances on state-wide tests has been documented by a number of researchers, but what is more difficult to determine are the root cause of this decline, the reason for the lack of equality between school systems, and the degree to which teachers can be held accountable.
(A) has been documented by a number of researchers, but what is more difficult to determine are
(B) has been documented by a number of researchers, but what is more difficult to determine is
(C) have been documented by a number of researchers, but what is more difficult to determine are
(D) is documented by a number of researchers, but what has been more difficult to determine are
(E) are documented by a number of researchers, but that which is more difficult to determine is
Concepts tested here: Subject-Verb Agreement + Tenses + Pronouns + Awkwardness/Redundancy• The present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present.
• 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.
• Whether the pronoun “what” is plural or singular depends on the number of the noun it refers to.
A: This answer choice incorrectly uses the plural verb "are" to refer to the singular pronoun "what"; please remember, whether the pronoun “what” is plural or singular depends on the number of the noun it refers to.
B: Correct. This answer choice correctly uses the singular verb phrase "has been documented" to refer to the singular noun "decline". Moreover, Option B correctly uses the singular verb "is" to refer to the singular pronoun "what". Additionally, Option B correctly uses the present perfect continuous tense verb "has been documented" to refer to an action that began in that past and continues into the present. Moreover, Option B correctly uses the simple present tense verb "is" to refer to an action taking place in the current time frame.
C: This answer choice incorrectly uses the plural verb "have been documented" to refer to the singular noun "decline". Further, Option C incorrectly uses the plural verb "are" to refer to the singular pronoun "what"; please remember, whether the pronoun “what” is plural or singular depends on the number of the noun it refers to.
D: This answer choice incorrectly uses the plural verb "are" to refer to the singular pronoun "what"; please remember, whether the pronoun “what” is plural or singular depends on the number of the noun it refers to. Further, Option D incorrectly uses the simple present tense verb "is documented" to refer to an action that started in the past and continues into the present; please remember, the present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present, and the simple present tense is used only to indicate actions taking place in the current time frame, indicate habitual actions, and state universal truths. Moreover, Option D incorrectly uses the present perfect tense verb "has been" to refer to an action taking place in the current time frame; please remember, the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, and state universal truths, and 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.
E: This answer choice incorrectly uses the plural verb "are" to refer to the singular noun "decline". Further, Option E incorrectly uses the simple present tense verb "are documented" to refer to an action that started in the past and continues into the present; please remember, the present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present, and the simple present tense is used only to indicate actions taking place in the current time frame, indicate habitual actions, and state universal truths. Additionally, Option E uses the needlessly wordy phrase "that which is", leading to awkwardness and redundancy.
Hence, B is the best answer choice.Additional Note: Please keep in mind that in this sentence "what" plays the role of a placeholder pronoun; rather than directly referring to a noun, it refers to a "that/who/whether" clause. Thus, "what" is singular because it refers to a singular clause.
To understand the concept of "Present Perfect Tense" on GMAT, you may want to watch the following video (~1 minute):
To understand the concept of "Present Perfect Continuous Tense" on GMAT, you may want to watch the following video (~1 minute):
All the best!
Experts' Global Team
close
08 May 2018, 07:36
20%
(01:21)
wrong 
