It's always good to learn different words, and contexts for using them, isn't it Andy?
It's funny, but I always think of an envelope or a little packet of flu remedy powder when I hear "sobre" - so I suppose that's why I tend not to use it in an "encima" context!
Do you find it funny how some words just seem to stick in your mind, and yet others constantly escape your efforts at recollection!?
It took me absolutely ages to be able to remember "agujero" (hole) but now it seems to be stuck in my brain forever - but for the life of me I cannot remember the word for bat (as in Dracula flying creature!) "murcielago".
There should be an accent over the "e", but I haven't got them on my keyboard
Have you got any favourite Spanish words or expressions?