a (an) [i q, #I, 3i ]    (순위: 2 - 초등 수준)  
Mean Used before nouns and noun phrases that denote a single but unspecified person or thing.
예문 1. A friend of mine in the United States called me yesterday. (미국에 있는 내 친구 하나가 어제 내게 전화를 했다)
2. a watch and chain (줄 달린 시계)
3. in a day or two (하루 이틀에)
4. A dog is faithful. (개는 충직하다)
5. for a week (1주간)