_____ friends can't hear _____. [ ]
A. He; he
B. He; him
C. His; he
D. His; him
答案:D
采用形位公差的未注公差值,在图样和技术文件中不须作任何标注和说明。
在理想导体表面外侧的附近介质中,磁力线()于其表面,电力线则与其表面相垂直。