"Che cosa" = "Cosa", both versions should be accepted.
When I was at elementary school my teacher wanted me to write every time "Che cosa", but I think that was a bit too strict. Italian is a very flexible language, if the version "Cos'è lui?" is not accepted, you should try to report it. :)
I was taught that "Cos'è" is a contraction of "Cosa" and "è", because it would otherwise sound weird transitioning between the two vowels. If you're talking at a normal conversation speed, it'd blend together anyways. It's less lazy that English contraction that seem to be caused by "I don't feel like pronouncing this vowel".
I found this sentence really confusing to translate...I got as far as "What what is he?" which made no sense at all!! In the end I gave up and asked for the answer. Very frustrating.
Why would the translation for this one be "what is he?" when "who" is listed as a valid translation option for "che"?
It is a valid translation, but not in this context: "è lui che mi ha chiamato" (it was he who called me) but "chi è lui?" (who is he). I think 'who' becomes 'che' only when joining sentences, but I might be wrong.
This might be helpful if you're also familiar with Spanish or French: I think of the Italian "che" the way I think of the Spanish "que" blended with properties of the French "qui" and can mean "what/that/which/who" depending on the context.
Anyone else have input on this? (Because I just made it up...)
I may be wrong, but I think "lui" can refer to anything that in Italian has a masculine noun: uomo, ragazzo, orso, pesce, cane, gatto, libro and so on. Since "he" refers only to males, sometimes the proper translation of "lui" is "it".
Another example of a bad example to be used for translation. Perhaps an explanation of usage might be appropriate. However, perhaps the example should be " Che cos'è lui? Un dottore"
Why is "what-d'yer-call-him?" Wrong? It is in the definition they gave us.