"Pro koho je ten zvláštní oblek?"

Translation: Who is the strange suit for?

[Stephen900455]

"For whom is the strange suit" or "The strange suit is for whom?" are grammatically correct and yes, people do say those. They should be acceptable translations, even if less commonly spoken.

[PhilCostin]

Can "ten" be read as "this"? Or only "the"?

[ValaCZE]

This would be" tento". "Ten" can be the or that.

[Mariba66]

Many words and sentences are without sound in this lesson.

[Rafaello201673]

I agree with Stephen! "for whom "should be accepted

[AgnusOinas]

And you know what? "For whom" is accepted. It has been accepted for 4 years at least - this exercise was last edited 4 years ago. So both Stephen's and your comment are "shouts in the dark" as we say in Czech ("výkřiky do tmy"), i.e. unjustified/irrelevant.