对材料性能,按照从高到低顺序排列的是()。 ["16MnR,Q235-B,20R","16MnR,20R,Q235-B","20R,16MnR,Q235-B","Q235-B,20R,16MnR"]
天津港一艘货船,近海航区,船长98m,如何配备救生设备?
GSM无线信道有几种TDMA帧的复帧结构,由于GPRS的引入,又增加了一种新的复桢结构,是哪种?() ["26帧","51帧","52帧","102帧"]
GPRS传输时的编码方式CS,在上行时由那个功能单元根据环境决定:() ["BSC基站控制器","PCU分组处理单元","MS手机","BTS基站"]
DN3000的塔体,按标准其允许的最大椭圆度为()。 ["25","30","15","12.5"]
凝汽器真空变送器拆校步骤?