One report concludes that many schools do not have, or likely to have,

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 this sentence is that many schools do not have and are not likely to have, enough computers to use them effectively.

Concepts tested here: Meaning + Parallelism

• Any elements linked by a conjunction ("or" and "nor" in this sentence) must be parallel.

A:
1/ This answer choice fails to maintain parallelism between "many schools do not have" and "likely to have"; remember, any elements linked by a conjunction ("or" in this sentence) must be parallel.

B:
1/ This answer choice fails to maintain parallelism between "many schools do not have" and "likely to have"; remember, any elements linked by a conjunction ("nor" in this sentence) must be parallel.

C:
1/ The sentence formed by this answer choice uses the clause "or are likely to have enough computers"; the construction of this clause incorrectly implies that many schools are likely to have enough computers to use them effectively; the intended meaning is that many schools are not likely to have enough computers to use them effectively.

D: Correct.
1/ The sentence formed by this answer choice uses the clause "nor are they likely to have enough computers", conveying the intended meaning - that many schools are not likely to have enough computers to use them effectively.
2/ Option D maintains parallelism between the clauses "many schools do not have" and "are they likely to have".

E:
1/ The sentence formed by this answer choice uses the clause "nor are not likely to have enough computers"; the construction of this clause incorrectly implies that many schools are likely to have enough computers to use them effectively; the intended meaning is that many schools are not likely to have enough computers to use them effectively.

Hence, D is the best answer choice.

All the best!
Experts' Global Team