2. Importance of Parts of Speech
Traditional grammar generally categorizes parts of speech into eight types: nouns, pronouns, verbs, adjectives, adverbs, prepositions, conjunctions, and interjection. In the process of learning a second language, learners have to mainly pay attention to how the word is used not what the word is (Khosravizadeh & Pashmforoosh, 2012). Knowing the grammatical class as contextual clues can help them to categorize the problematic written words, distinguish the function of words, and finally choose the correct meanings of the words. Ellis (1994) emphasized that it is essential to focus not only on meanings of words, but also on the association of meanings and word forms.