"What size is that shirt?"
Translation:Mitä kokoa tuo paita on?
I reported the missing verb. I submit this comment for the benefit of the volunteers.
(As a former Duolingo addict, I can tell you that it's "fun" to report something and then see in the comments that you've reported the same thing maybe even years earlier... But then it's also amazing to get a message that something you reported in a course you haven't touched for months or years was finally accepted!)
Really? You get a message when they accept your report? Wow. Never expected that!
Yes, I guess it depends on your settings (and I think they may have changed those, since I can't find the right one anymore...), but I get an email from Duolingo with the heading "Your suggestion was accepted!", just as I get an email when someone has replied in a discussion thread that I'm following. It's very satisfying!
Did it still not have "on"? It has been added, and shows at the top of this page for me, but I guess it'll take another week or so before it's there on all versions...
But kokoa is indeed a verb :-D It's the singular imperative of koota, which means to assemble or to gather together. But yes, not quite the verb needed here.