单选题 Because its pitch cannot easily be altered, the oboe serves as the standard which by the symphony orchestra is tuned.

【正确答案】 C

【答案解析】答案：C. which by: by which 分析：考点是介词+which 的从句结构参考译文：由于双簧管不能轻易被修改音频，常常用于乐队的标准调音。