弹簧的作用是使分离（）消除因支撑处存有间隙前后旷动而产生的噪声。 ["螺栓","螺母","杠杆","活塞"]
《动车组列车服务质量规范》供应品种多样，有高、中、低不同价位的预包装饮用水、盒饭等旅行饮食品，2元预包装饮用水和（）元盒饭不断供。 ["5","10","12","15"]
盒式诱变
Your network is suffering from regular outages. After troubleshooting， you learn that the transmit lead of afiber uplink was damaged. Which two features can prevent the same issues in the future？（） ["root guard","loop guard","BPDU guard","UDLD","BPDU skew detectio"]
半逆流型永磁筒式磁选机，给矿补加水管的用途是（）。 ["吹散矿浆","冲卸精矿","提高精矿品位","调节矿浆浓度"]
稳定角
