----I wonder how much for your services.
----The first two are free the third one costs $30.
A. while
B. until
C. when
D. before
网友回答
(答案→)A. while
B. until
C. when
D. before
解析:
这里考查while做连词,表示“然而”,表示两句话的对比关系,句意是:我想知道你的服务多少钱?---前两个是免费的,而第三个是30美元。选A。