Final answer:
The sentence 'They blame him for the accident' in passive voice is 'He is blamed for the accident.'
Step-by-step explanation:
The sentence 'They blame him for the accident' can be changed into the passive voice to express the action being done to the subject. In passive voice, the focus is on the action or the object of the sentence, not on who is performing the action. Therefore, the passive voice construction for this sentence would be: 'He is blamed for the accident.'