a가 어떤 의미로 쓰인건지 구분 부탁드립니다.
1-6번까지 구분해서 알려주세요

1. roem was not built in a day
2. he eats five meals a day
3. this is an interesting book
4. the fox is a cunning animal
5. there are seven days in a week
6. she keeps a diary three times a week