Final answer:
The sentence 'have they abandoned the institutions?' can be changed into passive voice by rearranging the sentence structure and using the auxiliary verb 'be' and the past participle form of the main verb.
Step-by-step explanation:
The sentence 'have they abandoned the institutions?' can be changed into passive voice by rearranging the sentence structure and using the auxiliary verb 'be' and the past participle form of the main verb. The passive voice transformation would be 'Have the institutions been abandoned by them?'