题目内容
The usual way to ensure reliable delivery is to provide the (16) with some feedback about what is happening at the other end of the line. Typically, the protocol calls for the receiver to send back special (17) frame bearing positive or negative (18) about the incoming frames. If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely.On the other hand, a negative acknowledgement means that something has gone wrong, and the frame must be transmitted again. An additional complication comes from the possibility that hardware troubles may cause a frame to (19) completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame and then waits for an acknowledgement, positive or negative, will hang forever if a frame is ever lost due to, for example, (20) hardware. （17）是（）
查看答案
搜索结果不匹配？点我反馈
更多问题
MIDI enables people to use (51) computers and electronic musical instruments. There are actually three components to MIDI, the communications " (52) ", the Hardware Interface and a distribution (53) called "Standard MIDI Files". In the context of the WWW, the most interesting component is the (54) Format. In principle, MIDI files contain sequences of MIDI Protocol messages. However, when MIDI Protocol (55) are stored in MIDI files, the events are also time-stamped for playback in the proper sequence. Music delivered by MIDI files is the most common use of MIDI today. （53）是（）
The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable (36) of the technical requirements for the software product.During the requirements definition phase, the requirements definition team uses an iterative process to expand a broad statement of the system requirements into a complete and detailed specification of each function that the software must perform and each (37) that it must meet. The starting point is usually a set of high-level requirements from the (38) that describe the project or problem.In either case, the requirements definition team formulates an overall concept for the system and then defines (39) showing how the system will be operated, publishes the system and operations concept document, and conducts a system concept review (SCR).Following the SCR, the team derives (40) requirements for the system from the high level requirements and the system and operations concept. Using structured or object-oriented analysis the team specifies the software functions and algorithms needed to satisfy each detailed requirement. （36）是（）
一个种群的年龄锥体呈下宽上窄的金字塔形，则该种类的年龄结构属于（）
论述题 什么是初级生产力？论述影响陆地生态系统初级生产力的因素及提高陆地生态系统初级生产力的途径。
微信支付 
支付宝支付