问题补充:
----What can I do for you?
----I’d like to buy a present for my teacher’s birthday, at a proper price, but of great value.
A. that
B. one
C. it
D. everything
答案:
A. that
(答案→)B. one
C. it
D. everything
解析:替代a+名词用one=a present,意思是:价格适合又很有价值的一份礼物。