题目内容
设有关系模式只(C，P，S，G，T，W)，各属性含义为：C课程，P老师，S学生，G成绩，T时间，W教室，其函数依赖集为：F=C→P,(S，C)→G，(T，W)→C，(T，P)→W，(T，S)→W则关系模式的关键字为 (35) ，R的规范化程度最高可达到 (36) 。若将R分解为关系模式组R1 (C，P)，R2(S，C，G)，R3(S，T，W，C)，则R1，R2，R3的规范化程度最高分别可达到 (37) ， (38) ， (39) 。 （35）处填（）。
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WWW is popular for its multimedia transmission and friendly (71) . Although the speed of network has been improved considerably in recent years, the rapid (72) of using the Internet, the inherited character of delay in the network and the Request/Response working mode of WWW still make the Internet traffic very (73) and give no guarantee on the Quality of Service. Because HTTP has no states, the web server cannot know the users’ demand and the users’ requests cannot be predicted Taking advantage of a cache mechanism and the time locality of WWW accesses, the browser can preserve the documents ever accessed in the local machine. By this means, for the documents in the local cache, the browser does not need to send the requests to the remote server or to receive the whole responses from the remote one Pre-fetching uses the space locality of accesses First, the users’ access requests are predicted according to the users’ current request. Secondly, the expected pages are fetched into the local cache when the user is brow sing the current page. Finally, the users can access these pages downloaded from the local cache. And this can reduce the access delay to some degrees. Pre-fetching is one kind of active caches that can cache the pages which are still not requested by the user. The application of pre-fetching technology in the web can greatly reduce the waiting time after users have sent their requests. This paper brings forward an intelligent technique of web pre-fetching, which can speed up fetching web pages. In this technique, we use a simplified WWW data model to represent the data in the cache of web browser to mine the association rules. We store these rules in a knowledge base so as to (74) the user’s actions. In the client sides, the agents are responsible for mining the users’ interest and pre-fetching the web pages, which are based on the interest association repository. Therefore it is (75) for the users to speed up the browsing. （75）处填（）。
面向对象软件技术的许多强有力的功能和突出的优点，都源于把类组织成一个层次结构的系统，一个类的上层可以有父类，下层可以有子类，这种层次结构系统的一个重要性质是（），由此性质可使一个类获得其父类的全部描述。
动态模型的描述工具是（）。
在软件的可行性研究牛，可以从不同的角度对进行研究，其中是从软件的功能可行性角度考虑的是（）。
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