题目内容
（请给出正确答案）
[多选题]
第 45 题：单元刚度矩阵的特性有哪些（）
A.对称的
B.奇异的
C.主对角项总是负的
D.主对角项总是正的
答案
ABD
如果结果不匹配，请 联系老师 获取答案
题目内容
（请给出正确答案）
答案
如果结果不匹配，请 联系老师 获取答案
题目内容
（请给出正确答案）
A.对称的
B.奇异的
C.主对角项总是负的
D.主对角项总是正的
答案
ABD
如果结果不匹配，请 联系老师 获取答案
更多“第 45 题：单元刚度矩阵的特性有哪些（）”相关的问题
阅读《国殇》中的一段文字，回答文后 45～47 问题。
操吴戈兮被犀甲，车错毂兮短兵接。旌蔽日兮敌若云，矢交坠兮士争先。凌余阵兮躐余行，左骖殪兮右刃伤。霾两轮兮絷四马，援玉桴兮击鸣鼓。天时坠兮威灵怒，严杀尽兮弃原野。
第 45 题 本节主要写了什么内容？
A.ensity
B.Shear Modulus
C.Young's Modulus
D.Poisson's Ratio
A.2750
B.3000
C.3333.33
D.4500
根据以下材料回答第 41～45 题：
Passage Three If you want to stay young , sit down and have a good think. This is the research result of Professor Faulkner , who says that most of our brains are not getting enough exercise and as a result, we are ageing unnecessarily soon.
Professor Faulkner wanted to find out why healthy farmers in northern Japan appeared to be losing their ability to think and to reason at a relatively age , and how the process of ageing could be slowed down.
He set about measuring brain volumes of a thousand people of different ages and occupations.
Computer technology enabled him to obtain precise measurements of the volume of the front and side sections of the brain , which relate to intelligence and emotion, and determine the human character.
Contraction of front and side parts—as cells die off –was observed in some subjects in their thirties, but it was still not evident in some sixty-and seventy –year-olds.
Faulkner concluded from his tests that there is a simple way to slow the contraction-using the head.
The findings show that contraction of the brain begins sooner in people in the country than in the towns. Those least at risk, says Faulkner, are lawyers , followed by university professors and doctors. White-collar workers doing routine work are, however, as likely to have shrinking brains as the farm worker, bus driver and shop assistant.
Faulkner’s findings show that thinking can prevent the brain from shrinking. Blood must circulate properly in the head to supply the fresh oxygen the brain cells need. “The best way to maintain good blood circulation is through using the brain , ” he says,” Think hard and engage in conversation. Don’t rely on pocket calculators.”
第 41 题 Professor Faulkner wanted to find out_________ .
A．how people’s brains shrink
B．the way of making people live longer
C．the size of certain people’s brains
D．why certain people aged sooner than others
在370名被试者中，选为高分组和低分组的被试者各有100人，其中高分组有70人答对第1题，低分组有40人答对第1题，那么第1题的难度为（）
A.0.55
B.0.35
C.0.45
D.0.65
