Question

whether early exposure to multiple writing systems enhances long - term linguistic flexibility ___ still under investigation in comparative studies of bilingual education programs. in a 2019 longitudinal study conducted by the max planck institute for psycholinguistics, researchers found that students exposed to both alphabetic and logographic scripts before age eight demonstrated greater task - switching efficiency and higher metalinguistic awareness scores than monolingual peers after five years of instruction.
18
mark for review
which choice completes the text so that it conforms to the conventions of standard english?
a is
b are
c have been
d to be

Explanation:

The subject of the sentence is the clause "Whether early exposure to multiple writing systems enhances long - term linguistic flexibility", which is a singular subject. In Standard English, a singular subject takes a singular verb. Option A "is" is a singular verb, while option B "are" is plural, option C "have been" is plural and in the present perfect tense (not suitable here as the sentence is about a current state of being under investigation), and option D "to be" is an infinitive and cannot function as a main verb in this context.

Answer:

A. is