[填空题]数据库系统中实现各种数据管理功能的核心软件是______。

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A teenager was unable to call an ambulance after her parents were shot in February because the family’ s internet phone service did not offer access to the 911 emergency number. A baby died in March for the same reason. Sad tales such as these led America’ s Federal Communications Commission (FCC) to vote on May 19th to require internet phone companies to offer a 911 service.
In so doing, the FCC seemed to have taken its first, big step towards imposing traditional telecoms rules on the internet--a contentious move given the fears that this will strangle what many still regard as an infant industry, especially if regulators elsewhere follow suit. But are the new rules really so bad
The new rules uphold a subset of telecoms policy, social objectives, which is much less burdensome than the FCC’S hugely unpopular economic regulation. Many providers of internet telephony--strictly, Voice over Internet Protocol (VOIP)--have for y
A. lack of a 911 service will dim the prospect of internet telephony to some extent.
B. popular economic regulators are supportive of telecoms.
C. the technical ability is essential to many providers.
D. incumbent operators manage phone service fairly for the time being.