Chinese has no morphology. So the relationship between part of speech and syntactic position has always been controversial. I studied a common verb. It's appearance in predicate position covers over 97%. It can also appears in subject, object, attributive position, but they together cover less than 3%. If we omit the impact from morphology and semantics, maybe frequency is the most important factor to determine a word's part of speech and syntactic position. Is there any similar study on English?