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问题 问答题 简答题

什么叫混凝土结构防护用渗透型涂料？

答案

参考答案：

能渗入混凝凝土内部并使混凝土表层具有憎水性，阻滞水与其他有害物质进入，延缓混凝土结构腐蚀破坏，并延长其使用寿命的材料。

单项选择题

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
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单项选择题 A型题

下列有关病毒体的概念，错误的是（）

A.完整成熟的病毒颗粒

B.细胞外的病毒结构

C.具有感染性

D.包括核衣壳结构

E.宿主细胞内复制的病毒组装成分
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