Question

I saw him opening the box. into change the voice.

Answer 1

The passive form of this should be:

He was seen opening the box.

Answer 2

The passive voice of the sentence: 'I saw him opening the box' is 'he was seen opening the box by me'.

• The rule of the change the active voice of the past indefinite tense is 'object + was/were + third form of the verb + other words + by + subject.'
• The object, in this case, is 'him'. It has to be changed in the subject that is 'he'. In active voice, the subject is 'I'. It has to be changed into the 'me'. ('We' is changed into 'us', 'she' is changed into 'her', 'he' is changed into 'him' and 'they' is changed into 'them'.) And the other words are 'opening the box'.
• The third form of the verb 'see' is used in the passive voice.