2. There/ be/ post office/ at/ corner/ street. A. There is an post office at the corner of the street. B. There is a post office at the corner of the street. C. There is a post office at the corner in the street. D. There is post office at the corner of the street.

`2`. There/ be/ post office/ at/ corner/ street.

A. There is an post office at the corner of the street.

`B`. There is a post office at the corner of the street.

C. There is a post office at the corner in the street.

D. There is post office at the corner of the street.

⇒ Câu `1` sai a → an vì post, chữ p không phải là nguyên âm ( o, a, e, u, i)

⇒ Câu `2` đúng 

⇒ Câu `3` sai vì At the corner of: Phía góc ở

⇒ Câu `4` sai vì phải có a trước post office → Vì post office không có s là danh từ số ít

→ There is+ a/ an+ N (số ít)