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Here is a detailed explanation to this question-
english_august wrote:
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.
(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic
Meaning is crucial to solving this problem:Understanding the intended meaning is key to solving this question; the intended meaning of this sentence is that in order to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are related to social and economic factors.
Concepts tested here: Meaning + Tenses + Comparison• The "would + simple present tense verb" construction is used to refer to hypothetical future actions and habitual actions in the past.
• Comparison must always be made between similar elements.
• The simple present tense is only 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.
A: This answer choice incorrectly uses the simple present tense verb "have" to refer to a hypothetical future action; please remember, the "would + simple present tense verb" construction is used to refer to hypothetical future actions, and the simple present tense is only 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 A incorrectly compares "know" to "now"; please remember, a comparison must always be made between similar elements.
B: This answer choice alters the meaning of the sentence through the phrase "social and economical"; the use of "economical" incorrectly implies that to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are
inexpensive; the intended meaning is that to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are
related to economic matters. Further, Option B incorrectly uses the simple present tense verb "have" to refer to a hypothetical future action; please remember, the "would + simple present tense verb" construction is used to refer to hypothetical future actions, and the simple present tense is only 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: This answer choice alters the meaning of the sentence through the phrase "social and economical"; the use of "economical" incorrectly implies that to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are
inexpensive; the intended meaning is that to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are
related to economic matters.
D: Correct. This answer choice uses the phrase "economic and social", conveying the intended meaning - that to develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the determinants of fertility that are related to economic factors. Further, Option D correctly uses the "would + simple present tense verb ("have" in this sentence)" construction to refer to a hypothetical future action. Additionally, Option D correctly compares "know" with "do".
E: This answer choice incorrectly compares "know" to "now"; please remember, a comparison must always be made between similar elements.
Hence, D is the best answer choice.All the best!
Experts' Global Team