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简答题 简述影响群落演替的主要因素.
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MIDI enables people to use (51) computers and electronic musical instruments. There are actually three components to MIDI, the communications " (52) ", the Hardware Interface and a distribution (53) called "Standard MIDI Files". In the context of the WWW, the most interesting component is the (54) Format. In principle, MIDI files contain sequences of MIDI Protocol messages. However, when MIDI Protocol (55) are stored in MIDI files, the events are also time-stamped for playback in the proper sequence. Music delivered by MIDI files is the most common use of MIDI today. （54）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. （16）是（）
WLANs are increasingly popular because they enable cost-effective connections among people and applications that were not possible in the past. For example, WLAN-based applications can enable fine-grained management of supply (11) to improve their efficiency and reduce (12) . WLANs can also enable entirely new business processes. To cite but one example, hospitals are using WLAN-enabled point-of-care (13) to reduce errors and improve overall patient care. WLAN management solutions provide a variety of other benefits that can be substantial but difficult to measure. For example, they can protect corporate data by preventing (14) through rogue access points.They can improve overall network management by integrating with customers’ existing systems. Fortunately, it isn’t necessary to measure these benefits to justify investing in WLAN management solutions, which can quickly pay for themselves simply by minimizing time- (15) deployment and administrative chores. （11）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. （62）是（）
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