“不经一番寒彻骨，怎得梅花扑鼻香。”这句话意在说明（）。 ["事物发展是曲折性和前进性的统一","只有参加社会实践才能获得正确认识","认识在实践中多次反复而无限发展","事物的发展前途都是光明的"]
烧结矿整粒的目的是什么？
遵章守纪、保证安全是维护铁路企业利益的需要。
增强顾全大局的意识，必须坚持小道理服从大道理。
A company is installing IP phones. The phones and office computers connect to the same device. To ensure maximum throughput for the phone data, the company needs to make sure that the phone traffic is on a different network from that of the office computer data traffic. What is the best network device to which to directly connect the phones and computers, and what technology should be implemented on this device? (Choose two.)（） ["hub","router","switch","STP","subinterfaces","VLAN"]
自升式塔式起重机的顶升接高系统由 （） 、 （） 和 （） 等三部分组成。
