科技档案管理和利用的基本单元是（）。A、文件 B、案卷 C、套 D、全宗

以下关于会计师事务所向审计客户提供评估服务的说法中正确的是（）。

A、如果审计客户要求会计师事务所提供评估服务，以帮助其履行纳税申报义务或满足税务筹划目的，并且评估的结果不对财务报表产生直接影响，通常对独立性产生不利影响

B、如果评估服务对会计师事务所发表意见的财务报表具有重大影响，且评估涉及高度的主观性，可采取防范措施将自我评价不利影响降低至可接受的水平

C、在审计客户属于公众利益实体的情况下，如果评估服务单独或累积起来对会计师事务所发表意见的财务报表具有重大影响，可采取防范措施将自我评价不利影响低降至可接受的水平

D、向审计客户提供评估服务可能会产生自我评价对独立性产生的不利影响

患者，女性，38岁，劳累性呼吸困难，进行性加重，乏力，气短，时有咯血，听诊心尖区有舒张期隆隆样杂音，临床诊断为风心病、二尖瓣狭窄。

该患者随后行二尖瓣人工瓣置换术，术后3天行超声心动图检查，检查中应该观察和测量的内容包括（）。

A.人工瓣的形态

B.人工瓣的位置

C.人工瓣的开闭情况

D.人工瓣瓣口流速及是否有关闭不全

E.是否存在瓣周瘘

根据《合同法》的规定，合同格式条款的使用必须合法，否则格式条款无效。下列各项中，属于无效的格式条款有( )。

A．理解发生争议的格式条款

B．违反法律强制性规定的格式条款

C．有两种以上解释的格式条款

D．以合法形式掩盖非法目的的格式条款

证券交易的原则是什么？主要的交易规则有哪些？它们对证券交易有何意义？

When the system upon which a transport entity is running fails and subsequently restarts,the(21) 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 connections can close the connection using a(22)timer. This timer measures the time the transport machine will continue to await an (23) of a transmitted segment after the segment has been retransmitted the maximum number of times.When the timer (24),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 (25) 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.

空白处（25）应选择（）

A.sequence

B.acknowledgment

C.connection

D.message