—Iwonderhowmuchyouchargeforyourservices．—Thefirsttwoare...

問題詳情：

— 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

【回答】

A. 考查連詞的用法。while表對比。

知識點：連詞

題型：選擇題