一个数据报通信子网允许各结点在必要时将收到的分组丢弃。设结点丢弃一个分组的概率为p。现有一个主机经过两个网络结点与另一个主机以数据报方式通信,因此两个主机之间要经过3段链路。当传送数据报时,只要任何一个结点丢弃分组,则源主机最终将重传此分组。试问: 目的主机每收到一个分组,连同该分组在传输时被丢弃的传输,平均需要经过几段链路
· For each extract, there are two tasks. Look at Task One, for questions 13-17, choose the key point about the transition from the lit A-H. Now look at Task Two, for questions 18-22, choose the statements in which they describe the transition of their companies from the list A-H. Task One—Transition Point · For questions 13-17, match the extracts with the key point, listed A-H. · For each extract, choose the key point stated. · Write one letter (A-H) next to the number of the extract. A taking a leap of faith B the right reposition vision C sharing ownership responsibilities D right pricing structure E good service F difficulties in transition G time consuming in transition H challenges in transition ____________
Task Two—Statements · For questions 18-22, match the extracts with the statement of what they do to their companies, listed A-H. · For each extract, choose the statement described. · Write one letter (A-H) next to the number of the extract. A It became a digital photography printer. B It has transited to a digital one completely. C Joint ventures soon get equal responsibilities. D They have faster delivery and lower prices. E It has transited into a digital one partially. F They provide good service and training. G It’s surprising to stand on top of the building. H They couldn’t build strong client relationship. ____________
· For each question 23-30, mark one letter A, B or C for the correct answer. Does tailoring still have appeal as a career choice
A. No, kids choose to go to university.
B. Yes, tailoring is seen as fashionable.
C. Not certain.