Julie Krueger wrote
Is the issue that in "sometimes I think I might still take it up—sometime.", the "sometime" is adjectival and "sometimes" is adverbial?
Before that, I'd written
True, it does. But if you say, 'We should have lunch sometimes,' it sounds (and is) wrong. In your penultimate sentence, 'sometimes' = 'occasionally.' Sometimes, I wish I'd studied mathematics. I did spend some time on it in high school; sometimes I think I might still take it up—sometime.
As far as I know, they're both adverbs. (And yet…) http://www.fortunecity.com/bally/durrus/153/gramch24.html Robert Paul, trapped in the basement of language