Topic has to be spoken on.

[tufguy]

"Topic that has to be spoken on today." Is this sentence correct?

Please check.

 

[tufguy]

No. You possibly mean 'This topic needs to be (has to be/is to be) discussed today'.

Could you please tell me what would be the passive sentence for "you have to speak on this topic today?"

 

[Tdol]

It would be this topic has to be spoken on today, but it's not very natural IMO.

 

[tufguy]

It would be this topic has to be spoken on today, but it's not very natural IMO.

So, we can't use passive voice for this kind of scenario?

 

[Raymott]

It depends on what you mean by "this type of scenario". The following is normal: "This subject needs to be spoken about."

 

[tufguy]

It depends on what you mean by "this type of scenario". The following is normal: "This subject needs to be spoken about."

"This topic needs to be spoken about". Is it also normal?

 

[Raymott]

Yes.

 

[tufguy]

That sentence seems a little less unnatural than the original, but I have to say that I wouldn't call it 'normal'.

So, should we adhere to the active voice only for these kind of sentences?

 

[Raymott]

It's normal in AusE.
Let's say there are social problems (and there are), but no media or politicians are willing to grapple with them. It's quite normal to say, "These problems need to be discussed"; "These problems need to be spoken/talked about."
I would use the first sentence, but they fall on a spectrum. 'Discuss' is close enough to 'talk about' or 'speak about' to pass the sentence as normal, in my opinion.

PS: And "subject, topic, matter, problem" also occur on a spectrum of naturalness.