"Ten kůň neběží příliš rychle."

[judygunson]

Why is "does not run very fast" wrong??

[VladaFu]

"běží" means "is running" just now, so the continuous form in English. "does not run" would be "neběhá".

[igamenir]

Also "very" would translated as "velmi" or "hodně". "Přiliš" has to be "too".