A national retail chain needs to design an IP addressing scheme to support a nationwide network. The company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate addressing scheme?（） ["255.255.255.0","255.255.255.128","255.255.252.0","255.255.255.224","255.255.255.192","255.255.248.0"]
注意的过滤器模型
金融投资
加工肉制品常用来着色之天然色素为（）。 ["食用红色5号","食用黄色5号","红曲色素","食用红色7号"]
永续年金
人是从哪而出的？仍要归于哪？
