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VALID: Affirming the sufficient, negating the necessary, existential before universal ...
INVALID: Affirming the necessary, negating the sufficient, universal before existential ...
There will never be a modifier or quantifier shift between the passage and the right answer. It's actually one of the fastest ways to eliminate wrong answers.
It seems that with some of the more difficult questions, the quantifier are subtly changed without erasing the possibility of whatever answer choice with such a change being the correct answer.
That question gave me a headache when I first encountered it a long time ago. But @DumbHollywoodActor nailed it. Follow J.Y's principle with negating necessary and negating sufficient when indicators kick in, and you should be fine.
How’s your negating ability? That has to be top notch. If not, I’d review that in the logic section. And I agree with @Pacifico. Keeping “blocking” and “bridging” in the back of my mind for NA really stops me from making a dumb mistake.