To change an active sentence to a passive one you do the following, for example:

"I kissed the cat." Active past

"The cat was kissed." (by me) the (by me) is not necessary. Passive past.

What you do is put the object "the cat" at the beginning of the sentence and add the correct version of the verb "to be" and follow it with the past particle of the verb.

So "I kiss the cat" Active present

" The cat is kissed." (by me) passive present

"I will kiss the cat." Active future

"The cat will be kissed." (by me) Passive future.

Etc.

This structure is used when we don't know who is performing the verb or when we don't want to say who is performing the verb.

It is a structure often used by politicians and lawyers.

I hope this helps

PS

When the sentence is more complicated you have to think it through but the principal is always the same.

No.

Hospital officials hope the Piano man will eventually be recognized by someone.

or

It is hoped by hospital officials that someone will eventually recognize the Piano Man.

or

It is hoped by hospital officials that the Piano Man will eventually be recognized by someone.

Those are all good English sentences.

I think it would be better like this...

Hospital officials hope that the Piano man will eventually be recognized.

You could also say:

Hospital officials hope that the Piano man will eventually be recognized by someone.

I don't think you're as far out as that. The word 'that' is out of place, you could change it so that:

"The Piano Man will be eventually recognized by someone that hospital officials hope."

becomes:

"The Piano Man will be eventually recognised by someone, is what the hospital officials hope."

Or if you wish for that part of the sentence to be passive also:

"The Piano Man will be eventually recognised by someone, is what is hoped by the hospital officials."

Or you can move the end bit up front:

"What is hoped by the hospital officials is that the Piano Man will be eventually recognised by someone"

Thanks you are great