No source answered every question

No source is such that (he or she answered every question)

(∀x: x was a source) ¬ x answered every question

(∀x: x was a source) ¬ every question is such that (x answered it)

(∀x: x was a source) ¬ (∀y: y is a question) x answered y

(∀x: Sx) ¬ (∀y: Qy) Axy

No source answered any question

every question is such that (no source answered it)

(∀y: y is a question) no source answered y

(∀y: y is a question) no source is such that (he or she answered y)

(∀y: y is a question) (∀x: x is a source) ¬ x answered y

(∀y: Qy) (∀x: Sx) ¬ Axy