Since no evidence has been found so far he was guilty he has to be set free.A. beforeB. w

问题补充：

Since no evidence has been found so far he was guilty, he has to be set free.

A. before

B. whether

C. that

D. when

答案：

A. before

B. whether

(答案→)C. that

D. when

解析：通过分析句子结构，可知这个句子中包含一个宾语从句，引导词在从句中不作任何成分，且没有实际意义，故只能用that。