…, let alone… / …, much less… / …, never mind…
can’t do one smaller thing, so certainly can’t do a bigger thing
can’t do an easy thing, so certainly can’t do a hard thing
(start with the lesser thing, then ‘let alone (something bigger)’)
I can’t remember my first kiss, let alone if it was any good.
We don’t have enough money for a hamburger, let alone steak.
He can hardly speak English, never mind Chinese.
I didn’t notice you had gone, never mind cared.
His cat can hardly walk down the stairs, much less catch a mouse.
The voters didn’t like his appearance, much less his policies.