Surely the present tense in Spanish covers what we might say in English as both 'The horses eat' or 'The horses are eating'. The present participle crops up a lot in English, in circumstances that I would have thought would normally just be said using the present tense in Spanish (and French for that matter...).
Yes and no. It'll be wrong for this exercise.
Los caballos se comen- (literally translated) the horses are eating. (real world translation) the horses are edible...
True in parts of Spain, but totally different meaning.
But, add an article and an noun, like 'the grass' and we get:
Los caballos se comen el pasto- the horses eat the grass/ the horses are eating the grass