什么叫绝缘闪烙?
参考答案:
绝缘材料在电场作用下,尚未发生绝缘结构的击穿时,在其表面或与电极接触的空气(离子化气体)中发生的放电现象,称为绝缘闪烙。
E-mail, as well as telephones, _____ an important part in daily communication.
A.is playing
B.have played
C.are playing
D.played
轴瓦钨金应为强度较高、耐磨性较好的()。