单选题 ______ that you've got something to do in the evening, I won't keep you.
A. Since B. Now C. When D. For

【正确答案】 B
【答案解析】[考点] 原因状语从句
[解析] now that的意思是“由于，既然”，引导原因状语从句，因为原句中已给出了that，故选B。