普通车床光杆的旋转最终来源于()
A、溜板箱
B、进给箱
C、主轴箱
D、挂伦箱
参考答案:B
Tom ________ watch TV after supper ________ last night. [ ]
A. wasn't; /
B. didn't; on
C. doesn't; on
D. didn't; /
变压器铁芯的作用?