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问题 单项选择题 A1型题

食管癌的早期症状是（）

A.吞咽困难

B.胸骨后疼痛

C.食物或黏液反流

D.进粗食时有暂时性胸骨后停留或异物感

E.消瘦

答案

参考答案：D

解析：食管癌常见的早期症状是进粗食时有暂时性胸骨后停留或异物感，然后逐渐出现吞咽困难。

单项选择题

When the system upon which a transport entity is running fails and subsequently reatarts, the ___34___ 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 promble.

The still active side of a half-open connections using a ___35___ timer. This timermeasures the time transport machine will continue to await an ___36___ of a transmitted segment after the segment has been retransmitted the maximum number of times. When the timer ___37___, 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 restart, half-open connections can be teminated more quickly by the use of the RST segment. The failed side returns an RSTi to every segment i that it receives. When the RSTi reaches the other side, it must be checked for validity dased on the ___38___ 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.

36（）

A. reset

B. acknowledgment

C. synchroizer

D. sequence
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选择题

甲、乙两个重物（G甲＝G乙）在起重机钢索的牵引下竖直向上运动，它们的s t图像如图1（a）、（b）所示，则                                                （   ）

A．甲、乙的速度大小相等

B．乙通过的路程较长

C．乙受到钢索的拉力较大

D．甲、乙受到的合力大小相等
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