— I wonder how much you charge for your services— The first two are free the third costs

问题补充：

— I wonder how much you charge for your services．

— The first two are free the third costs $30．

A. while

B. until

C. when

D. before

答案：

A. while

B. until

C. when

D. before

解析：考查连词：A. while然而，虽然，当…时候B. until直到C. when当…时候D. before在…前面，句意：--我想知道你的服务要多少钱？--前两个是免费的，第三个是30美元。选A。