–May I go to the concert with you?– I’m afraid not you have a ticket because I have only

问题补充：

–May I go to the concert with you?

– I’m afraid not you have a ticket, because I have only one.

A. since

B. if

C. unless

D. though

答案：

A. since

B. if

(答案→)C. unless

D. though

解析：句意：我可以和你一起去听音乐会吗？恐怕不行。除非你有一张票，因为我只有一张。since 自从；既然；if 如果；unless 除非，如果不；though 尽管。根据句意可知选C。