下面哪一组导游人员的分类是按照导游职业性质来划分的( )

A．专职导游人员、业余导游人员、临时导游人员
B．海外领队、全陪、地陪、讲解员
C．普通话导游人员、外语导游员、方言或少数民族语言导游人员
D．初级导游人员、中级导游人员、高级导游人员、特级导游人员

When the system upon which a transport entity is running fails and subsequently restarts, the (1) information of all active connections is lost. The affected connections become half-open, as the side that did not fail does not yet realize the problem.

The still active side of a half-open connection can close the connection using a (2) timer. This timer measures the time the transport machine will continue to await an (3) of a transmitted segment after the segment has been retransmitted the maximum number of times. When the timer (4) , the transport entity assumes that either the other transport entity or the intervening network has failed. As a result, the timer closes the connection, and signals an abnormal close to the TS user.

In the event that a transport entity fails and quickly restarts, half-open connections can be terminated more quickly by the use of the RST segment. The failed side returns an RST i to every segment i that it receives. When the RST i reaches the other side, it must be checked for validity based on the (5) number i, as the RST could be in response to an old segment. If the reset is valid, the transport entity performs an abnormal termination.

2（）

A.give-up 

B.abandon 

C.quit 

D.connection