—Mum I need a new schoolbag.--But didn’t I buy you three months ago?A. itB. thatC. on

问题补充：

—Mum, I need a new schoolbag.

----But didn’t I buy you three months ago?

A. it

B. that

C. one

D. another

答案：

A. it

B. that

(答案→)C. one

D. another

解析：it.指同一东西, one指同类型的东西; another意为:又一个,再一个.