What is the passive voice of 'the teacher didn't check the papers'

I can't tell u the answer but i'll tell u how to answer it.

Explanation:

Here's how to approach turning an active-voice sentence like this into passive voice. The general principle is to make the object the subject. In this sentence, the object is "the student." So the full subject will be "The student." First, check whether the full subject is first-person, second-person, or third-person.