"He is too fat to run fast."
Translation:Li estas tro dika por rapide kuri.
PMEG gives this explanation: http://bertilow.com/pmeg/gramatiko/i-verboj/kun_rolvortetoj.html
It's something to do with clarifying the role of the verb within the sentence, although it can indeed be left out sometimes. For the sentence of this discussion, it would sound a bit odd to me if "por" were left out.
If you @Novantico would replace the simple present tense run by present continuous tense running , just as a thought experiment, when you think of these kind of sentences, it is much clearer what por is needed force... since these are equal (enough here) :
too fat for running
too fat to run
Qomprende amigo ?
Actually I think the problem is rather the inconsistent use of to and for in English for he same thing, but that is just my personal add-on. BTW since for and por are written so similar it could be a good mnemo tech thing...
just mina du cents...
does the adverb always precede the verb in Esperanto "rapide kuri" as opposed to "kuri rapide", or should I have reported this?
From what I understand so far, "in order to". I believe in these types of sentences in English, the preposition "to" serves a similar function or the same as "por" in Esperanto, rather than strictly forming part of the infinitive. It may be also because we tend to drop the "in order" part in English. I can't see this with 100% certainty. Maybe someone with a better understanding of this particular aspect of grammar when know better than I woul, or could explain it in more detail. Just thought this may help.