下列关于施工图预算编制的表述，不正确的是( )。

A．施工图预算通常分为建筑工程预算和安装工程预算两大类
B．施工图预算编制方法分为单价法和实物法两类
C．实物法编制施工图预算所用的人工、材料和机械台班的单价都是当时当地的实际价格
D．单价法工作量大，计算过程繁琐

(1) is used to ensure the confidentiality, integrity and authenticity of the two end points in the private network. (2) , an application-layer protocol, authenticates each peer in an IPsec transaction. IKE negotiates security policy, determining which algorithm may be used to set up the tunnel. It also handles the exchange of session keys used for that one transaction.

Networks that use (3) to secure data traffic can automatically authenticate devices by using (4) , which verify the identities of the two users who are sending information back and forth. IPsec can be ideal way to secure data in large networks that require secure connections among many devices.

Users deploying IPsec can (5) their network infrastructure without affecting the applications on individual computer. The protocol suite is available as a software-only upgrade to the network infrastructure. This alows security to be implemented without costly changes to each computer. Most important, IPsec allows interoperability among different network devices, PCs and other computing systems.

4（）

A．characteristics

B．associated links

C．digital certificates

D．attributes