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WebSQL is a SQL-like (61) language for extracting information from the web. Its capabilities for performing navigation of web (62) make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a (63) , all the pages that can be reached from a given URL through. (64) that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common (65) Interface. （63）是（）
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Virtualization is an approach to IT that pools and shares (71) so that utilization is optimized and supplies automatically meet demand. Traditional IT environments are often silos, where both technology and human (72) are aligned around an application or business function. With a virtualized (73) , people, processes, and technology are focused on meeting service levels, (74) is allocated dynamically, resources are optimized, and the entire infrastructure is simplified and flexible. We offer a broad spectrum of virtualization (75) that allows customers to choose the most appropriate path and optimization focus for their IT infrastructure resources. （73）是（）
WebSQL is a SQL-like (61) language for extracting information from the web. Its capabilities for performing navigation of web (62) make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a (63) , all the pages that can be reached from a given URL through. (64) that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common (65) Interface. （65）是（）
The usual way to ensure reliable delivery is to provide the (16) with some feedback about what is happening at the other end of the line. Typically, the protocol calls for the receiver to send back special (17) frame bearing positive or negative (18) about the incoming frames. If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely.On the other hand, a negative acknowledgement means that something has gone wrong, and the frame must be transmitted again. An additional complication comes from the possibility that hardware troubles may cause a frame to (19) completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame and then waits for an acknowledgement, positive or negative, will hang forever if a frame is ever lost due to, for example, (20) hardware. （20）是（）
The metric assigned to each network depends on the type of protocol. Some simple protocol, like RIP, treats each network as equals. The (91) of passing through each network is the same; it is one (92) count. So if a packet passes through 10 network to reach the destination, the total cost is 10 hop counts. Other protocols, such as OSPF, allow the administrator to assign a cost for passing through a network based on the type of service required. A (93) through a network can have different costs (metrics). For example, if maximum (94) is the desired type of service, a satellite link has a lower metric than a fiber-optic line. On the other hand, if minimum (95) is the desired type of service, a fiber-optic line has a lower metric than a satellite line. OSPF allow each router to have several routing table based on the required type of service. （94）是（）
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