As previously stated, the passive voice in English is formed by combining a form of the verb to be with the past participle of a transitive verb. Its overall structure and its contrast with the active ...

The voice of the verb is distinct from its tense. Don't confuse the passive voice with the past tense. (Sentence 2 happens to be in the past tense, but 3 is not; both 2 and 3 are in the passive voice.

5. *Be flying some birds. 6. *Hank's father is resembled by Henry. In the grammatical propositional structure, voice like tense and moods is an operator. The first feature set is [±Pass] (Passive).

However, in each pair one sentence uses the active ... pupil’ would change to ‘The pupil passed the exam’. STEP 4 - ‘Two slices of bread were taken’ is in the passive voice.