Have seen play

They both seem ok to me.

The "whom" is technically correct, but rarely used in that position. These days, "whom" shows up only immediately after prepositions in most cases, so it's rarely used as a direct object.

Again, it's correct, but will be seen by many as "overly" correct.

But isn't there a rule that says that there can be no passive form of bare infinitives.

Debpriya DeBut isn't there a rule that says that there can be no passive form of bare infinitives.

That would be news to me.

Could you explain that more?

"They have made him return the money."
The passive of this would be "He has been made to return the money."
The passive form does not use a bare infinitive.

Debpriya DeThe passive form does not use a bare infinitive.

Not with the verb to make, but that doesn't make it universally true.

This is the man she she should have chosen.
The cake I watched her make was delicious.
The song you heard me play was by Barber.
And your original example.

All show this rule is not

Debpriya De"They have made him return the money."The passive of this would be "He has been made to return the money."The passive form does not use a bare infinitive.

I think you're talking about pulling the person or the thing out of the active version to make the subject of a passive sentence. In either case, you can get some really bad sentences. Even the

Debpriya De"He is the best footballer I have seen play."
"Whom did you see play ?"

Here are diagrams to show where the gaps are.

He is the best footballer I have seen ____ play. (I have seen him play.)
Whom did you see ____ play? (You did see whom play?)

Neither structure is passive, so I don't know how the thread got

Okay, I get it now.

Debpriya DeOkay, I get it now.

Good, because I'm still confused!

CJ