The（）schemeinadatabasesystemisresponsibleforthedetectionoffailuresandfortherestorationofthedatabasetoastatethatexistedbeforetheoccurrenceofthefailure.

单项选择题（）statementcanperformacalculationandstoretheresultinavariablesothatitcanbeusedlater.

A.Assignment
B.Control
C.I/O
D.Declaration

单项选择题Dataitemsareaddedordeletedfromthelistonlyatthetopofthe（）.

A.queue
B.stack
C.tree
D.linearlist

单项选择题（）meansthataprogramwrittenforonecomputersystemcanbecompiledandrunonanothersystemwithlittleornomodification.

A.Portability
B.Reliability
C.Availability
D.Reusability

单项选择题（）hasbecomeafactofmodemlife，withmillionsofpeoplenowshoppingon-line.

A.E-mail
B.E-commerce
C.E-Iearning
D.E-communication

单项选择题Thedata（）includesthefunctionofupdatingdataonadatabase，andretrievingdatafromadatabase.

A.management
B.storage
C.analysis
D.communication