The purpose of the commutator and brushes on a DC generator is to（）

A . Develop ductility B . Improve machining qualities C . Relieves stresses D . All of the above

A .  To review RMAN control file and recovery catalog metadata and ensure that its correct B .  To delete RMAN backup-related metadata from the recovery catalog C .  To create metadata in the control file and the recovery catalog related to backup set pieces  D .  To create a report that lists database backups E .  To rebuild the recovery catalog

A . To keep all the members in the group work together． B . To make the people there understand the meaning of work． C . To find a way to solve the generation gap． D . To help people enjoy their work．

A . counterbalance the crank throws on the crankshaft B . keep the engine running smoothly between power stroke C . provide a belt-driving surface for the operation of auxiliary machinery D . prevent the engine from overspeeding

A .  It allows you to select the SCN that you want to restore to. B .  It allows you to select the log sequence number you want to restore to. C .  It allows you to select the timestamp you want to restore to. D .  It allows you to manually stop the restore at any time as online redo logs are applied. E .  None of the above.

A . provide energy to operate the engine between power impulses B . neutralize the primary inertia force of the crankshaft C . reduce the shock of starting loads on the main bearings D . prevent the engine from operating at critical speed

A .  Recover database datafiles from physical disk backup sets. B .  Recover required incremental backups from physical disk backup sets. C .  Recover required archived redo logs from physical disk backup sets. D .  Apply incremental backups to recover the database.  E .  Apply archived redo logs to recover the database.

A . Serves as a backup for the main tow hawser in case of failure B . Provides weight and flexibility to the total tow makeup C . Lengthens the main tow hawser to keep the tow in step D . Distributes the towing load

A . to map a known DLCI to an IP address B . to map a known IP address to a MAC address C . to map known SPID to a MACaddress D . to map a known DLCI to a MAC address E . to map a known IP address to a SPID F . to map a known MAC address to an IP addre

A．To welcome health care professionals B．To promote certain health services C．To discuss health workforce shortages D．To promote careers in health care

A．To keep all the members in the group work together. B．To make the people there understand the meaning of work. C．To find a way to solve the generation gap. D．To help people enjoy their work.

A．To inform. people the severity of the millennium bug. B．To accuse some comes for being inactive. C．To advise people to abandon the computers. D．To tell the readers the way to solve the millennium bug problem.

A. to describe how American children spend their summer. B. to explain the needs of the modern working families. C. to discuss the problems of the current school calendar. D. to persuade parents to stay at home to look after their kids.

A．To compare guided tours B．To discover new places of interest C．To introduce a book series D．To show ways of writing for children

A.To advertise their spray. B.To advertise their new shoes. C.To complain the bad quality of the shoes. D.To answer the complaint.

A．To point out similarities in Emerson"s essays and poems B．To prepare the students to read an essay by Emerson C．To compare Emerson"s concept of universal truth to that of other authors D．To show the influence of early United States society on Emerson"s writing 此题为多项选择题。

A．To invite people to take a breath in the Bay of Naples. B．To advise people to telephone Newmarket Air Holidays Ltd. C．To persuade people to tour in the area of the Mediterranean Sea. D．To attract people to go to Sant' Agata or Sorrento for sightseeing.

A．To interest students in a career in counseling. B．To recruit counselors to work in the placement office. C．To inform. students of a university program. D．To convince local merchants to hire college students.

A．To publicize a community event B．To solicit donations for a special cause C．To ask for public feedback on a proposal D．To announce a program change

A．To outline contrasting types of economic system. B．To explain the science of economic systems. C．To argue for the superiority of one economic system. D．To compare barter and money-exchange markets.

A．To advise that TV should be used for educational purpose B．To describe the harmful effects of TV on children C．To explain traditional views of influences that TV has had on children D．To suggest that television cannot be blamed for problems it doesn't cause

A．tell what the family do for Thanksgiving Day B．tell how the family spend Thanksgiving Day C．introduce foods served on Thanksgiving Day D．introduce the American Thanksgiving Day