used after a negative statement to emphasize how unlikely a situation is because something much more likely has never happened

Some people never even read a newspaper, let alone a book. 有些人从不看报纸，更不用说读书了。

He could hardly touch his knees, let alone his toes.

There wasn't enough to keep us occupied for an afternoon, let alone the whole weekend.

I barely had time to take a shower, let alone make home-cooked meals.

I wouldn't want to be in the same room as that woman, let alone date her.

See also: let adverb