单项选择题
A.0.3Mpa B.0.5Mpa C.0.6Mpa D.1MPa
A.19~20mm B.19~21mm C.19~22mm D.19~23mm
A.1mm B.2mm C.3mm D.4mm
A.减小 B.增加 C.不变 D.铜耗增加、温升不变
微信扫一扫,加关注免费搜题