A transport layer protocol has several responsibilities, One is to create a process-to-process (program-to-program) communication; TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocol is to create a (2) and error-control mechanism at the transport level. TCP uses a sliding (3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.空白（5）处应选择（） A.ports。 streams。 packets。 cells。
A transport layer protocol has several responsibilities, One is to create a process-to-process (program-to-program) communication; TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocol is to create a (2) and error-control mechanism at the transport level. TCP uses a sliding (3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.空白（4）处应选择（） A.packet。 time。 error。 phase。
A transport layer protocol has several responsibilities, One is to create a process-to-process (program-to-program) communication; TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocol is to create a (2) and error-control mechanism at the transport level. TCP uses a sliding (3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.空白（3）处应选择（） A.path。 window。 frame。 diagram。
某品牌商品的销售情况如图10.2所示。 若想按产品类别分别累计销售量，可使用分类汇总命令，汇总的结果如图10.3所示。 在进行分类汇总前，应先对数据清单中的记录按（1）字段进行排序；选择"数据/分类汇总"命令，并在弹出的"分类汇总"对话框中的"选定汇总项"列表框内，选择要进行汇总的（2）字段，再单击"确认"按钮。 空白（1）处应选择（） 产品。 销售日期。 销售地点。 销售量。
阅读以下关于网络系统数据备份方面的叙述，回答问题1至问题3。 博学教育集团总公司的信息管理部门决定为信息中心的计算机网络制订一个相对完善的网络系统数据备份的整体解决方案。经讨论与分析后，普遍认为在该数据备份方案中必须实施以下要点： （1）选用专业级的网络备份管理软件，以代替原来使用的普通备份软件或者由网络操作系统中所提供的备份软件。 （2）选用可靠的存储介质，以优质磁带为主，辅以少量可记录光盘和若干可卸式硬盘或软盘片。 （3）选用性能价格比良好的自动加载磁带机，作为网络系统数据备份的主要备份设备。 （4）制定合理的备份策略。可能选用的备份策略允许包括完全备份方式、增量备份方式和差分备份方式，以及这些方式的组合。例如，完全备份方式可以是每天对网络系统进行全部数据的完全备份。增量备份方式可以是只在每周五进行一次完全备份，在以下的周一到周四只对当天新的或被改动过的数据内容进行备份。差分备份方式可以在每周五进行一次完全备份，在以下的周一至周四，每天对当天与上周五相比有不同的数据（新的或被改动过的）进行备份。 （5）建立起备份磁带和有关存储介质的严格管理制度，并由专人审计与监督备份的执行情况。
A transport layer protocol has several responsibilities, One is to create a process-to-process (program-to-program) communication; TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocol is to create a (2) and error-control mechanism at the transport level. TCP uses a sliding (3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.
空白（1）处应选择（）
