单项选择题
事务T1、T2如下图所示（注：PRINT (A+B)表示打印账户A和B的总金额）。
其中事务T1从账号B向账号A转50元钱，事务T1显示账号A和B的总金额，请设计一个服从两段锁协议的加锁解锁方案，使得在并发调度两个事务时，可有效地避免数据的不一致状态。下列方案中不正确的是___________。
A．
B．
C．
D．
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【S1】Homes could start been connected to the Internet through electrical outlets. 【S2】 In this way, consumers and business may find easier to make cheaper telephone calls under new rules that the Federal Communications Commission began preparing on Thursday. 【S3】 Taking together, the new rules could profoundly affect the architecture of the Internet and the services it provides. 【S4】 They also have enormous implications for consumers, the telephone and energy industries, equipment manufacturers. Michael K. Powell, the F.C.C.chairman, and his two Republican colleagues on the five-member commission said that 【S5】 a 4-to-1 vote on Thursday to allow a small company providing computer-to-computer phone connections to operate in different rules from ordinary phone companies, would ultimately transform. the telecommunications industry and the Internet.【S6】 'This is a reflecting of the commission's commitment to bring tomorrow's technology to consumers today,' said Mr. Powell. He added that 【S7】the rules goveming the new phone services sought to make them as wide available as e-mail,【S8】 and possibly much less expensive than traditional phones, and given their lower regulatory costs. At the same time, 【S9】 once while the rules allowing delivery of the Internet through power lines are completed, 【S10】 companies could provide consumers with the ability to plug their modems directly into wall sockets, just like they do with a toaster, or a desk lamp.
【S1】
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