Nine in ten parents said there were significant differences in their approach to educating their children compared with __________ of their parents.
A. those
B. one
C. both
D. that
18世纪法国物理学家(),根据有关扭力方面的知识,提出了电荷的反比平方律,这是近代电磁学理论第一个()定律。
古德伊尔发明橡胶的硫化法,解决了生胶变粘发脆问题,使橡胶具有较高的__________和________,橡胶才真正进入工业实用阶段。
20/5t桥式起重机主钩上升控制过程中,将电动机接入线路时,将控制手柄置于上升第一档,KMUP、KMB、和KM1相继吸合,电动机()转子处于较高电阻状态下运转,主钩应低速上升。
A. M1
B. M2
C. M4
D. M5