问题 单项选择题

联结三个刚片的铰结点,相当于的约束个数为()。

A.3

B.4

C.5

D.6

答案

参考答案:B

解析:

平面体系几何组成分析中的铰分两种:一种是单铰,另一种是复铰。一般连接两个刚片的铰为单铰,连接两个以上刚片的铰为复铰。复铰的作用相当于两个单铰。由此类推,从减少自由度的观点看,连接n个刚片的复铰可以相当于n-1个复铰,将减少2(n-1)个自由度,即相当于2(n-1)个约束。 [点评] 此题考察平面体系几何组成分析中铰的概念以及单铰与复铰之间的关系,此类问题的另一种形式是先要明确复铰连接的刚片数量,然后依据关系作进一步的计算。

问答题 简答题
单项选择题

Caesar was right. Thin people need watching. I’’ve been watching them for most of my adult life, and I don’’t like what I see. When these narrow fellows spring at me, I quiver to my toes. Thin people come in all personalities, most of them menacing. You’’ve got your "together" in person, your mechanical thin person, your condescending thin purism, your tsk-tsk thin person, your efficiency-expert thin person. All of them are dangerous.In the first place, thin people aren’’t fun. They don’’t know how to goof off, at least in the best, fat sense of the word. They’’ve always got to be adoing. Give them a coffee break, and they’’ll jog around the block. Supple them with a quiet evening at home, and they’’ll fix the screen door and lick S & H green stamps. They say things like "there aren’’t enough hours in the day". Fat people never say that. Fat people think the day is too damn long already.Thin people make me tired. They’’ve got speedy little metabolisms that cause them to bustle briskly. They’’re forever rubbing their bony hands together and eyeing new problems to "tackle". I like to surround myself with sluggish, inert, easygoing fat people, the kind who believe that if you clean it up today, it’’ll just get dirty again tomorrow.Some people say the business about the jolly fat person is a myth, that all of us chubbies are neurotic, sick, sad people. I disagree. Fat people may not be chortling all day long, but they’’re a hell of a lot nicer than the wizened and shriveled. Thin people turn surly, mean, and hard at a young age because they never learn the value of a hot-fudge sundae for easing tension. Thin people don’’t like gooey soft things because they themselves are neither gooey nor soft. They are crunchy and dull, like carrots. They go straight to the heart of the matter while fat people let things stay all blurry and hazy and vague, the way things actually are. Thin people want to face the truth. Fat people know there is no truth. One of my thin friends is always staring at complex, unsolvable problems and saying, "The key thing is fat people never say that." They know there isn’’t any such thing as the key thing about anything.

Which of the following statements can best describe the behavior of most thin people as ascribed by the passage

A.Thin people could never find themselves having enough time for leisure.

B.Thin people are seldom unable to find themselves having nothing to do.

C.Thin people are never lazy in doing things useful.

D.Thin people are fussily annoying and particularly disgusting.