не говоря уже о

not to mention; let alone

→ не
phrase Rare #45,666
not to mention; let alone Used to emphasize that the second thing is even more notable or unlikely than the first. The exact English translation depends on whether the preceding statement is positive or negative.
RU: Он не умеет плавать, не говоря уже о дайвинге.
EN: He can't swim, let alone go diving.