"Het snelle paard loopt."
Translation:The fast horse is walking.
As Voyta said, the other two are abstract nouns, that don't describe physical objects. I'm a native speaker too, and 'rapid horse' sounds completely alien to me. The only non-abstract noun that I would apply 'rapid' to is 'water', and even then I'm more likely to make it the adverb 'rapidly' and apply it to what the water's doing.
I asked my friend who is a native Dutch speaker:
Hey, Dutch question. Does "lopen" mean both "to walk" and "to run"? What's the most common way to say "to walk" and "to run"?
The act of walking is "lopen". Hiking and walking for pleasure is "wandelen". Running is "rennen" or "hardlopen". "Hardlopers zijn doodlopers" = going too fast will kill you.
So it's wrong when translators say that "lopen" also means "to run"?
Not necessarily. "De tentoonstelling loopt van januari to december". The exhibition runs from January to December. That kind of running.
Ah. But it does not mean "run" in the sense of body locomotion.
Het snelle paard loopt? - Site translation: The fast horse is walking or walks. Loop- run, hij loopt- he runs. My answer was the fast horse runs which is apparently wrong. So not sure I understand this twist taking the word from run to be walk especially since there is a motion for horse "galop".