As you know, we can never transform the followings to 'passive voices' because they have no objective on the sentences.

1) The sun rised.  rises OR rose

2) He lied in the bed.  Lies OR layed

On the other hand, what if the sentences is like these?

1) A gentleman spoke to her.

2) We can't think of such a thing.

3) We have never heard of him since.

4) No one has ever spoken to me like that before.

5) People speak well of him.

6) I gave up this job.

As I know, the forms of the verbs are one of these : 1) transitive verb + adverb, 2) intransitive verb + preposition

In this case, is it possible that we use them like the followings?

1) She was spoken to by a gentleman.  

2) Such a thing can't be thought of by us. 

3) He have never been heard of by us since. 

4) I never have been spoken to by anyone like that before.

5) He is spoken well of by people.

6) This job was gaven up by me.    given up

1) She was spoken to by a gentleman.   OK

2) Such a thing can't be thought of by us.  Grammatical, but to me it's unnatural.

3) He has never been heard of by us since. With the word 'since' in the sentence, it seems to me you should say 'heard from' rather than 'heard of'.  If the idea of 'us' is important, I would not use this passive sentence -- I'd use the active version instead.  If 'we' is not important, then omit 'by us'.

4) I never have been spoken to by anyone like that before. I'd simply omit 'by anyone' -- its placement is awkward in the sentence and it really isn't necessary anyway.

5) He is spoken well of by people. 'By people' is completely unnecessary.  Leave it out.

6) This job was given up by me.  Grammatical, but not natural as a passive sentence.