以下哪种仪器能有效判断变压器有载调压开关故障（）
A.兆欧表
B.介损电桥测试仪
C.有载调压开关测试仪
D.变压器变比测试仪
参考答案：C
—Do you think you will fail in the math exam?
—_________. I am not good at it at all.
A．I think not
B．I’m afraid not
C．I’m afraid so
D．I hope so
