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问题 单项选择题

独立柱柱顶受集中荷载如图所示，柱底a-a截面的受力状态为（）。

A.压力和剪力

B.压力和弯矩

C.弯矩和剪力

D.压力、剪力和弯矩

答案

参考答案：D

解析：图中杆件与地面为固定连接，当施加如图所示方向的力F时，首先判断a-a截面处受到的压力和弯矩，由于是固定连接，那么还应受到剪力。

多项选择题

招标文件的作用有( )。

A．招标文件是投标人准备投标文件和参加投标的依据

B．招标文件是招标程序的依据

C．招标文件是招标人和投标人订立合同的基础

D．招标文件是招标投标活动当事人的行为准则和评标的重要依据

E．招标文件是招标成功的保证
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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．vanished

B．drifted

C．shifted

D．escaped
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