更不用说；更别提
Merriam-Webster Online Dictionary
let alone (conjunction)to say nothing of not to mention - used especially to emphasize the improbability of a contrasting example he would never walk again let alone play golf Sports Illus. how many ever see an Ambassador or Minister, let alone a President Robert Lacville
Merriam-Webster Online Thesaurus
let alone (conjunction)to say nothing of
SYNONYMS:
much less, never mind, still less