Yes of course the parts of speech ARE important. English grammar classifies words based on 8 parts of speech: the verb,[run] the noun,[boy] the pronoun,[he] the adjective,[funny] the adverb,[slowly] the preposition,[on] the conjunction, [and] & the interjection or exclamation.[ah!] Each part of speech explains not what the word is, but HOW the word is used. In fact, the same word can be a noun in one sentence and a verb or adjective in the next.

i think sometimes it is

1. Ability/knowledge of foreign language . 2. Skill to express effectualy and enough data/material for speech . 3. Confidence and sameless .. and so on . So, it is not easy .

your question is not comprehensible , could you modify it or say it in another way ?