钢材是在严格的技术条件下生产的材料，它具有的特点是（）
A.材质均匀
B.强度高
C.塑性和韧性好
D.导热性差
E.易锈蚀
参考答案：A, B, C, E
高压验电笔是用来检查高压网络变配电设备，架空线，电缆是否带电的工具。
The Education Department says that school safety has set off alarm bells with frequent reports of serious accidents ________ students got injured or killed.
A．after which
B．in which
C．by which
D．for which
