---Can I help you?-I’d like to buy a gift for my mother at a proper price but of great

问题补充：

---Can I help you?

---I’d like to buy a gift for my mother, at a proper price but of great use.

A. that

B. one

C. anyone

D. everything

答案：

A. that

(答案→)B. one

C. anyone

D. everything

解析：考查代词。That特指上文提到的某一个；one泛指任何一个；anyone指任何一个；everything指每件事；句意：能帮你什么忙吗？——我想给我的母亲买一件礼物，一个价格合理但是有大用的礼物。可知此处泛指任何一个同类的礼物，故选B。