______ are web sites that search the web for occurrences of a specified word or phrase.

Web网页木马就是木马利用Web页面传播的一种方式，Web网页木马的最典型特点的是（）。

OR指令的作用是: 。( )

基于Web的信息系统开发技术主要包括Web网络协议、Web网页技术和数据库连接技术。

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。

F1系列PLC—OR指令表示（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。