胶管骨架材料中的线材分为纤维线材和()线材。
参考答案:金属
Wuhan is hot at this time of year. You'd better _clothes. [ ]
A. to pack heavy
B. pack heavy
C. pack light
D. to pack light
判断通电导体的磁场方向用()。
A、安培定律
B、左手定则
C、右手定则
D、楞次定律