Which of the following database object is used to speed up access to desired data ？

A、the columns often used for queries

B、the columns often used for sorting and grouping

C、the columns with unique values, such as primary key

D、the columns updated frequently but rarely used for queries

A．Read and send e-mail.

B．Browse the Web and even watch short dramas for cell phone users.

C．Download music, games and video files.

D．All the above.

A．Read and send e-mail.

B．Browse the Web and even watch short dramas for cell phone users.

C．Download music, games and video files.

D．All the above.

A.REVOKE ACCESS ON DATABASE FROM USER bob

B.REVOKE CONNECT ON DATABASE FROM USER tom

C.REVOKE tom FROM ACCESS ON DATABASE BY USER bob

D.REVOKE tom FROM CONNECT ON DATABASE BY USER bob

A．Only British citizen has access to the New York Teaching Fellows program.

B．Candidates should have graduated from the City University of New York.

C．It's not required to have full certification for the candidates.

D．Most candidates will teach in the key schools of the city.

A．GPRS offers faster access to data through network connections, so customers should pay more.

B．Motorola Inc. is the inventor of the cell phone.

C．Previously Motorola only supplied mobile phone manufacturers with some of its chips.

D．Motorola Inc. is known for its high-class engineering culture.

A．GPRS offers faster access to data through network connections, so customers should pay more.

B．Motorola Inc. is the inventor of the cell phone.

C．Previously Motorola only supplied mobile phone manufacturers with some of its chips.

D．Motorola Inc. is known for its high-class engineering culture.

A．People may not see the significance of certain new technologies immediately after they appear.

B．It may take several years for people to realise the impact of new technologies on our culture.

C．New technologies are likely to make it difficult to preserve valuable information.

D．New technologies will enable us to have access to more valuable information.

A．It cannot be carried around easily.

B．It can be read from many places worldwide.

C．It can be accessed immediately after issued.

D．It requires little delivery cost and time.

A.IDcardreaders

B.Serverrackdoors

C.Biometricdevices

D.Lockeddoors