单位时间内通过过水断面的水体体积称为水的体积流量（）
A. 正确
B. 错误
Which two of these are advantages of placing the VPN device parallel to the firewall?（）
A. high scalability
B. the design supports a layered security model
C. firewall addressing does not need to change
D. IPsec decrypted traffic is inspected by the firewall
E. there is a centralized point for logging and content inspectio
代理服务器主要具有：节省连入Internet的IP地址、（）和防火墙等功能。
A. 减少出口流量
B. 收发邮件
C. 文件打印
D. 路由
芽变选种的果树株系只要经过初选，表现性状优良，即可在生产上推广应用。
A. 正确
B. 错误
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