方位角的精度依据哪几个因素（）。 ["测向仪的种类","场地自然状况","频率带宽","信号强度","传播条件"]
The existing terrestrial radio system has a number of basic flaws which（）. ["can be overcome by using traditional techniques","cannot be overcome by satellite system","can be overcome by satellite and digital techniques","cannot be tackled by any modern system"]
根据炊事作业指标，炊事车展开时间应当不大于20分钟。
From the ship owner’s point of view,（）is the most important advantage Inmarsat providing with. ["business opportunity","good-quality radio telephone conversations","telex service","both B and C"]
无线电导航属于（）。 ["无线电定位","无线电测定","射电天文","工科医应用"]
焊接检验的一般过程是什么？
