Passive voice in cases when principal clause is followed by noun clause

Question

Active: People say that he lives abroad now.
Passive1: It is said (by people) that he lives abroad now.
Passive2: He is said to live abroad now.

Active: We understand that he dislikes children.
Passive1: It is understood (by us) that he dislikes children.
Passive2: He is understood to dislike children.

In the above cases where a principal clause is followed by noun clause, the passive voice can be formed in the above two ways. I noted that in the first way the change is made only to principal clause and not the noun clause.

But then in a test I came across a question:

Active: We hope that we shall win the match.
Passive (my ans) : It is hoped (by us) that we shall win the match.
Passive (correct answer): It is hoped that the match will be won by us.

When to make changes to only the principal clause and when to both?

Answer 1

There is no absolute rule that governs when you should use the it version and when not. In my opinion (I speak American English), the it version is the more conversational of the two:

They say he doesn't like children. ^colloquial

People say he doesn't like children. ^{conversational}

It's said he doesn't like children. ^{slightly circumspect conversational}

He is said to dislike children. ^{educated register conversational verging on stilted}

Again, to my American English ear:

We understand he lives abroad. ^neutral

It is understood he lives abroad. ^formal

He is understood to live abroad. ^stilted

Answer 2

when Noun clause has an object we change that too to passive voice.