– May I play basketball with my friends now?– No you’ve finished your homework.A. since

问题补充：

– May I play basketball with my friends now?

– No, you’ve finished your homework.

A. since B. ifC. unless

答案：

解析：

试题分析: 句意：我可以现在和我的朋友踢足球吗？不行，除非你已经完成了作业。Since自从if如果unless

除非。完成作业是踢足球的条件故选C。