Question

---- 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

Answer 1

A

考查连词用法。本题考查了while表示转折的用法，意为：然而；句意：—我想知道这服务你要收多少钱？—最先的两次免费，而第三次收费30。