盘簧常用于:()。 ["A.重型机械的缓冲装臵。","B.仪器和钟表的储能装臵。","C.各种车辆的减振装臵。","D.电接触器。"]
以下哪类跑腿服务允许发布?() ["代送午餐、书信","陪聊天、逛街","提供粉末类快递服务","代买车票"]
()是由母岩的风化产物、火山物质、有机物质等碎屑物质在常温常压下经过搬运、沉积和石化作用,最后形成的岩石。 ["变质岩","沉积岩","火成岩","岩浆岩"]
通常取紧固件边距为()。 ["A.紧固件直径的2倍","B.不小于被连接板件总厚的2倍","C.紧固件直径的3倍","D.不小于被连接板件总厚的3倍"]
以下哪个商品不允许在淘宝上出售?() ["电脑摄像头","无线隐形耳机","手机","信号探测器"]
简述BTS3812基站信号在各板间的流向?