Can I help you?-I’d like to buy a present for my father’s birthday at a proper pr

问题补充：

--- Can I help you?

---I’d like to buy a present for my father’s birthday, at a proper price but of great use.

A. the one

B. one

C. which

D. it

答案：

A. the one

(答案→)B. one

C. which

D. it

解析：考查指示代词。One指代可数名词单数，表泛指；that指代可数名词单数或不可数名词，表特指；the one是特指，相当于that；it指代上文提到的人或物，也可指代性别不详的人。这里泛指“一个物美价廉的礼物”，属于泛指，且present是可数名词，故用one指代present，故选B。