let alone

phr

• ①[通常用于否定句]遑论,更不必说了(=to say nothing of)
  • She can't read, let alone [much less] write.她不会读,至于写更不必说了。
  • They had never even heard of the Han, let alone its successors the Wei and the Chin.乃不知有汉,无论魏、晋(★见陶潜桃花源记)。