51、根据渐进分析，表达式序列：n4, lgn, 2n, 1000n, n2/3, n!从低到高排序为（  ）。

A、Ign,1000n, n2/3, n4, n!, 2n

B、n2/3,1000n, lgn, n4, n!, 2n

C、lgn,1000n, n2/3, 2n, n4, n!

D、Ign, n2/3, 1000n, n4, 2n, n!

52、Regardless of how well designed, constructed, and tested a system or application may be, errors or bugs will inevitably occur. Once a system has been（  ），it enters operations and support.

Systems support is the ongoing technical support for user, as well as themaintenance required to fix any errors, omissions,or new requirements that may arise. Before an information system can be（  ）, it must be in operation. System operation is the day-to-day, week-to-week, month-to-month, and year-t-year（  ）of an information system's business processes and application programs.

Unlike systems analysis, design, and implementation, systems support cannot sensibly be（  ）into actual phases that a support project must perform. Rather, systems support consists of four ongoing activities that are program maintenance, system recovery, technical support, and system enhancement.Each activity is a type of support project that is（  ）by a particular problem,event, or opportunity encountered with the implemented system.

A、designed

B、implemented

C、investigated

D、analyzed

A、supported

B、tested

C、implemented

D、constructed

A、construction

B、maintenance

C、execution

D、implementation

A、broke

B、formed

C、composed

D、decomposed

A、triggered

B、leaded

C、caused

D、produced