简述信道编码的基本思想？

列车从甲站开向乙站的正常行驶速度是60km/h，有一次由于某种原因列车从甲站开出时迟了5min，司机把速度提高到72km/h，才刚好正点到达乙站，则甲、乙两站间的距离是多少千米？

Passage 1If you have never seen a power plant, you might find it hard to imagine how enormously complex the equipment is or how much heat is generated by the boilers or how much coal it takes to fuel the furnaces for just one day.During the course of a day, the boilers at one of our power plants, Morgantown, for example, can turn 24 million gallons of water into steam. That generating plant alone uses 9,900 tons of coal in its furnaces in just one day. Potomac Electric Power Company (PEPCO) uses so much coal that we have purchased two 80-car unit trains to facilitate the delivery process. And Morgantown alone can produce over 25 million kilowatthours of electricity in a single day’’s operation.Electricity is produced by spinning large magnets inside a coil of wire within the generator. The faster we spin the magnets, the higher will be the voltage of the electricity produced. Electricity leaves a PEPCO generator at between 13,800 and 24,000 volts.The next step in the process occurs when electricity passes through a transformer where the voltage is stepped up to continue on its journey. A transmission wire is like a small diameter pipe. Stepping up the voltage is like increasing water pressure, thus speeding the flow of energy through the system.Passage 2Because the aircraft industry needs ever-increasing quantities of aluminium plate, new equipment has been designed to automate the making of it. It includes a huge heat-treatment furnace, a crane that lifts hot metal plates without damaging them, and a computer system that can manage the complete flow of work.Five years ago, Europe’’s aircraft industry needed only 8,000 tonnes of aluminium plate a year for its products. Last year the figure reached 21,800 tonnes. By 2004 it should total 30,000 tonnes. Each airliner contains 180 tonnes of it. That is why the plant is being rebuilt to increase both the quality and the amount of its product.Aluminium is alloyed with other metals and cast into ingots, and the surface of the ingots is smoothed off. After pre-heating, it is rolled in a mill that can take 3.75-m-wide slabs. The new equipment can make the process more efficient and can produce a better product. For example, computers control the temperature of the hot plates, the rate at which they pass through the mill, the speed of cooling it with water, and so on.The new plant can handle twice the throughput of the one that it is replacing, thanks to the completely automated and computerized process.

某商品流通企业经销的某种商品有甲、乙、丙、丁四个供应商可供选择。该企业依据有关标准确定了评审供应商绩效的指标体系。每项指标分为5个档次：好、较好、一般、较差、极差。每个档次的分值分别为：好，5分;较好，4分;一般，3分;较差，2分;极差，1分。根据四个供应商前两年的供货情况，依据供应商绩效评审指标体系给每个供应商打分，具体得分如下表所示。

该企业每年进行一次供应商绩效评审。评审合格的供应商可作为下一年度的合格供应商，评审不合格的供应商将被淘汰。在评审供应商绩效时，不仅以绩效指标好坏来确定供应商的取舍，还充分考虑了外来客观因素的影响。该商品流通企业经过了与丁供应商的长期合作，双方形成了紧密的关系。在产权关系上，双方互相投资，参股;在组织上双方互派人员加入对方的有关业务活动。

根据丁供应商与该企业在合作中形成的紧密关系，丁供应商应属于（）供应商。

A．联盟型

B．渗透型

C．短期交易型

D．长期伙伴型

益气托毒法的常用方剂是（）

A.透脓散

B.仙方活命饮

C.黄连解毒汤

D.托里消毒散

E.清肝解郁汤

执行下面的程序段后，AL寄存器中的内容应该是( )。
MOVAL，03H
MOVBL，09H
SUBAL， BL

A．0FAH

B．04H

C．06H

D．86H