Learn English – better way to write multiple Nota Bene? i.e “n.b., n.b.b.” e.t.c

If you want to go by the Latin, argumentum ad ignorantiam pluralises as argumenta ad ignorantiam (arguments to ignorance), and similarly reductio ad absurdum pluralises as reductiones ad absurdum (reductions to absurdity) – the point is that ad ignorantiam and ad absurdum (and, for that matter, the principii in petitio principii) serve as adjectival phrases, and are thus indeclinable in Latin.

1. "Mitt Romney, Paul Ryan to Awkwardly Hug, High Five" was The Onion’s snarky way of insinuating that when Romney selected Ryan as his running mate he condemned both of them— stuffy, constrained, powerful middle-aged white men who are not even ideologically compatible —to three months of pretending close friendship and demonstrating their credentials as "ordinary guys" by practising the conventional gestures of male intimacy, with which they will not be comfortable.

2. Scores here is not a verb but a plural noun which in the singular means the quantity 20. The number of dead is not certain at the time of writing; it is apparently not so many that it could be appropriately approximated by "Hundreds", but is more than would be implied by "dozens", so the Times selects the intermediate value "scores".

How do you learn to read headlines better? Basically, you have to know the language and the culture they're referring to better—which isn’t very helpful. Happily, it’s not really important to be a fluent reader of headlines.