Distress traffic（）all messages relating to the immediate assistance required by the ship in distress, including search and rescue communications and signals for locating. ["consists of","is consisted of","consisted of","are consisted of"]
用一部测向机获得的方位角带有误差，产生误差的原因有（） ["设备或该设备所用的技术","测向场地","传播","操作员"]
下列哪个选项不是项目管理需求增加的驱动力量？（） ["产品生命周期缩短","知识爆炸","第三世界封闭经济快速发展","更多的强调产品而忽视顾客","公司小型化"]
测向机在30MHz以下测向时，由电离层引起的测向误差（）。 ["与测向机处接收射线的仰角成正比","随电离层高度的增加而增加","随反射次数的增加而增加","随发射机距离变小而减少"]
打开“搜索结果”对话框，按（）组合键。 ["CTRL+F","WIN+F","CTRL+P","WIN+P"]
X射线和γ射线有哪些主要性质？
