Data in secondary memory won't be lost when power is interrupted.

A．Gathering secondary data is costly．

B．Collecting secondary data is time consuming．

C．Few sources exist for secondary dA

D．It is not accurate enough．

B．Secondary？data？are？collected？through？interviews,？surveys;？primary？data？are？derived？from？books,？newspapers,？Internet,...

C．Primary？data？has？fewer？resource？requirements;？secondary？data？has？more？resource？requirements.

D．Primary？data？are？fresher？and？more？updated;？secondary？data？tends？to？be？of？higher？quality.

E．Secondary？data？are？less？suitable？to？match？our？need;？primary？data？are？better？matching？our？nee

D．

A.Standby node

B.Check point node

C.Secondary data node

D.Secondary name node

A.talk with customers and suppliers

B.collect data on the Internet

C.observe what happens

D.do experiment

A.Both technologies guarantee an identical copy of data on the secondary node

B.Only MySQL can maintain a time-delayed copy of data on the secondary node

C.Both technologies use the TCP/IP stack as their primary transmission medium

D.DRBD uses shared-disk technology

A.Backup

B.Name node

C.Data node

D.Secondary name node

A．How much does the data cost

B．For what purposes were the data collected

C．What language is used in the host country

D．Was the data available on the Internet

The data station usually means a(71)unit that provides data for transmission, that accepts transmitted data, and that performs all functions necessary for communication with another functional unit. Data stations may be divided into two kinds, the primary stations and the secondary stations, (72)control functions.In(73)data link control, the primary station is the data station that supports the primary control functions of the data link, generates commands to be transmitted, and interprets received responses. Specific responsibilities assigned to the primary station include initialization of control signal interchange, organization of data flow and actions regarding error control and error recovery functions. The secondary station executes data link control functions as (74)by the primary station, interprets received commands and (75) responses to be transmitted.

A．performance

B．functional

C．capacity

D．quality