薄板和薄带试样原横截面积测量误差不应超过（）。
A.±1%
B.±2%
C.±3%
参考答案：B
Near the church _____ cottage. [ ]
A. was such an old
B. had a so old
C. was such old a
D. is so an old
下列哪项属于电源内阻（）
A.专用供电变压器内阻
B.自耦变压器内阻
C.灯丝变压器内阻
D.高压变压器内阻
E.其他电器内阻
