根据地震脉冲的视周期或主频与炸药量的关系证明大炸药量激发的波视周期大、主频低。
参考答案：对
— Alison, I'm sorry. I can't come to the wedding with you tomorrow morning.
— ______?
— My grandma was severely ill, so I have to stay in the hospital to look after her. [ ]
A. How is it
B. How come
C. So what
D. What's the problem
预定义技术的主要通信工具是定义报告。报告形式有多种，下列哪一种可以表明外部实体、过程和文件之间的数据流动 ( )
A．叙述文字
B．流程图
C．逻辑判定表
D．数据字典
