问题
选择题
----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
答案：B
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。