E.g., "On my spare time I'm working on an essay" or "In my spare time I'm working on an essay".
Which is correct? Both in/on are prepositions, but "in my spare time" sounds more idiomatic to me. A friend corrected me, and now I'm curious.
Which is correct (or are both)?.
too basic. Just a reference to a graph doesn't seem to be a useful tool to suggest an appropriate response to a question. All it shows, is just what other people prefer. And if that was what you were trying to convey, then an appropriate response would have just been a simple "It's a matter of preference" and then maybe a link to theGoogle Ngram Viewerto support such a statement. – Souta Sep 13 '12 at 14:56