公安工作是依据( )保卫国家安全与社会治安秩序的专门工作。A．法律 B．法规 C．

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.

4（）

A.stops 

B.restarts 

C.expires 

D.abandons

粉尘对人体可有以下作用（）。

A．致纤维化

B．刺激

C．中毒

D．致敏

E．以上全部

萎缩

A．发育正常的器官或组织的体积缩小
B．肾盂积水，肾实质萎缩
C．实质细胞数量或体积增加而致器官或组织的体积增大
D．静脉性充血
E．红细胞自心腔内或血管内逸出

二维超声心动圈常用的基本切面有哪些？

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