The title is clear, I suppose. This question appeared when I saw someone who's a native English commented something like this:
We'd have to ask an alien and I haven't seen one for days.
In my opinion, the phrase for days is quite the same as for ages or for a long time. That makes me think, it's supposedly used when someone has seen it before. For instance:
After the divorce, I haven't seen her for days
In my example above, I believe, it means I've known my ex-wife and I've met her, but after the divorce I haven't seen her for ages in a long time interval.
That would be different, if the case is I never saw her that means we were not even married. Like when I say:
Never did I meet your daughter, Paul. Is she beautiful?
That means that I truly never saw Paul's daughter before.
My final question, are those sentences (in the title) equivalent? Thanks in advance!
Best Answer
We use 'for days, weeks, months, years' (etc) to mean a period of time for which it is sensible to use the term chosen. For example, 'for days' means 'a small number of days'. The maximum is not exactly defined, but if the time was more than 14 days we might decide to say 'for weeks'. It has been raining for hours, my dog has been missing for days, my mother has been away for weeks, that supermarket has been closed for months, I haven't driven a car for years.
I know of two alternative US slang meanings, in US gay culture - an exclamation of surprise or shock 'You won the sweepstake? For days!' and one arising out of Black culture in the 1960s, meaning 'a lot of something' - e.g. 'A certain singer has a lovely face, great figure, and legs for days'. I do not believe that either of these meanings is intended.
The remark about not having seen an alien 'for days' is a joke. Nobody has seen any aliens. The joke pretends that aliens exist (when everyone knows that they have not so far been found). Consider: to know what my brother is planning, you'd need a mind-reader, and I haven't seen one of those for weeks.