Original sentence: "What are new here are (1) XYZ and (2) PDQ."
Correcting this sentence in a text and it just feels wrong. In order to make sure I change it correctly, I tried searching for:
- The type of inversion this structure is, and thus,
- The rule for verb agreement.
Alas, no luck. The best I could do was try different combinations in Google Scholar, among which I found 138 instances of "What is new here are" (and, of course, 3940 results for "is ... is").
"Is ... are" feels much better, and the only explanation I can think of is that "is" agrees with "what", while "are" corresponds to what follows. Still, I can't really face the world with confidence in that explanation.
Can anybody point to the specific rule regarding this structure?