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问题 单项选择题

发展容错技术可提高计算机系统的可靠性。利用元件冗余可保证在局部有故障的情况下系统的正常工作。带有热备份的系统称为 (122) 系统。它是 (123) ，因此只要有一个子系统能正常工作，整个系统仍能正常工作。

当子系统只能处于正常工作和不工作两种状态时，我们可以采用图A的并联模型(见图 1-21)，若单个子系统的可靠性都为0.8，图示的三个子系统并联后的系统的可靠性为 (124) 。当子系统能处于正常和不正常状态时，我们可以采用图B所示的表决模型(见图1-21)，若图中有任何二个或三个子系统输出相同，则选择该相同的输出作为系统输出。设单个子系统的可靠性为0.8时，整个系统的可靠性为 (125) ；若单个子系统的可靠性为0.5，整个系统的可靠性为 (126) 。

（122）是（）

A．并发

B．双工

C．双重

D．并行

答案

参考答案：C

单项选择题 共用题干题

男，22岁，因急性失血输入新鲜血液200ml。输血后出现巩膜轻度黄染，病人诉尿液呈酱油色，怀疑为异型输血后发生溶血。

临床常用来诊断溶血的指标是（）

A.ALT

B.TBIL

C.ALP

D.AST

E.AMY
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单项选择题

Until recently, most population growth has occurred in relatively dense urban environments. In (91) words, even if we were witnessing rapid population growth, that would not mean that the (92) were filling in with people. (93) , the urban areas would tend to become more crowded. Historically, we find that people have moved to (94) the jobs were. Jobs were usually in ports or locations with many natural (95) . After transportation became relatively cheap, other geographical locations became (96) of economic activity. One factor that determines where people will move to, even when transportation becomes cheap, is (97) . And individuals working in cities (98) higher incomes than those working in (99) areas. Hence, population has tended until the 1970s to (100) in our major urban centers. Recently population has (101) out of the Northeast to the South and to the West for the more pleasant climates. If people did not (102) from living in large cities, there would likely be a much more even population distribution (103) our entire land area. Probably, if this (104) the case, there would be less concern over population (105) Indeed, one need only (106) a cross-country drive or plane trip to realize how (107) populated these United States really are. This is not to say that we should or should not do something about (108) growth. The shortage of people in certain areas merely demonstrates that overpopulation in the United States is really only a problem in (109) urban environments. And this problem may be slowly correcting (110) .

A．other

B．another

C．one another

D．those
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