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  3. Online services are managed by a host system that maintains a base of inform

Online services are managed by a host system that maintains a base of inform

游客2024-06-27  58
问题     Online services are managed by a host system that maintains a base of information available to satellite users. Users of so-called "dumb" terminals (i.e.those without processing capability) simply access the information base via programs stored on the system. Personal computer (PC) users typically access the host through a modem(调制解调器). A PC software program serves as an interface (接口) between the server and a PC, allowing the user to operate through the online system and select different databases using a keyboard or a mouse.
    National and regional online systems usually have local telephone numbers that PC modems can call to access either a local information base or an indirect long-distance connection, thus reducing long-distance telephone fees. Some online systems allow users to copy large volumes of information onto a local memory storage device, which also reduces the time the user is connected to the online system.
    Besides offering a great number of different information bases, ranging from full-text journal libraries to reports of missing children, online services allow users to, for example, reserve airline tickets, buy stocks, purchase goods, and communicate with other users. In exchange for the service, users usually pay a monthly membership fee. They may also pay to connect to various databases on the service or to download information.
选项 A、a base of information
B、dumb terminals
C、a host system
D、a satellite
答案 A
解析 本题为推理题。根据文章第一段第一句话"Online services are managed by a host system that maintains a base of information available to satellite users．”可知，网络服务通过中央系统来管理，而中央系统则具有供网络使用者用的信息库。由此可见，网络服务为使用者提供信息库。因此答案为A。
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