下列哪个选项不是为了TCP协议保证可靠性传输？（）

数据库系统中采用封锁技术的目的是为了保证（）。

网络认证技术只是单向认证技术

VPN主要采用了4项技术来保证安全，它们分别是加密技术、密钥管理技术、身份认证技术和(28)。

VPN主要采用了4项技术来保证安全。它们是加密技术、密钥管理技术、身份认证技术和(28)。

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

（）, or drum is used for hauling in or letting out the wires or ropes which will fasten the ship to the shore.

A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

The （） is used for hauling in or letting out the wires or ropes.

Vessels must be（）valid certificate of nationality or certificated of registry or license.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。