Question

they laughed at his warnings and objected to all his proposals change the sentence into passive voice
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Answer 1

Answer:

Active voice: They laughed at him.

Passive voice: He was laughed at (by them).

When we transform a sentence form active into passive voice:

The object of the active voice sentence ( in our case him) becomes the subject of the passive voice sentence (he).

The verb consists of a form of the verb to be in the corresponding tense ( in our case past simple - was) + the past participle of the verb in the active voice sentence ( in our case laughed)

If we want to mention who does the action, we use the by phrase (in our case by them).

Hope this helps

Answer 2

Answer:

All of his proposal were laughed at this warning and objected by them