问题 单项选择题

图14-42所示结构,当I1不变,I2增大叫,则支座反力X1(绝对值)将()。

A.增大

B.减小

C.不变

D.不确定

答案

参考答案:A

解析:

由超静定结构特性可知,刚度大的杆件承受的力也大,因此当支座连接的杆件刚度增大时,支座反力将增大。故正确答案选择为A。

阅读理解

It is hardly surprising that clothing manufacturers(生产商) follow certain uniform standards for various features of clothes.What seems strange, however, is that the standard adopted for women is the opposite of the one for men.Take a look at the way your clothes button.Men’s clothes tend to button from the right, and women’s form the left.Considering most of the word’s population----men and women----are right-handed, the men’s standard would appear to make more sense for women.So why do women’s clothes button from the left?

History really seems to matter here.Buttons first appeared only on the clothes of the rich in the 17th century, when rich women were dressed by servants.For the mostly right-handed servants, having women’s shirts button from the left would be easier.On the other hand, having men’s shirts button form the right made sense, too.Most men dressed themselves, and a sword drawn from the left with the right hand would be less likely to get caught in the shirt.

Today women are seldom dressed by servants, but buttoning form the left is still the standard for them.Is it interesting? Actually, a standard, once set, resists change.At a time when all women’s shirts buttoned form the left, it would have been risky for any single manufacturer to offer women’s shirts that buttoned from the right.After all, women had grown so used to shirts which buttoned from the left and would have to develop new habits and skills to switch.Besides, some women might have found it socially awkward to appear in public wearing shirts that buttoned from the right, since anyone who noticed that would believe they were wearing men’s shirts.

小题1:What is surprising about the standard of the clothing industry?

A.It has been followed by the industry for over 400 years.

B.It is different for men’s clothing and women’s.

C.It woks better with men than with women.

D.It fails to consider right-handed people.小题2:What do we know about the rich men in the 17th century?

A.They tended to wear clothes without buttons.

B.They were interested in the historical matters.

C.They were mostly dressed by servants.

D.They drew their swords from the left.小题3:Women’s clothes still button from the left today because        .

A.adopting men’s style is improper for women

B.manufacturers should follow standards

C.customs are hard to change

D.modern women dress themselves小题4:The passage is mainly developed by         .

A.analyzing causes

B.making comparisons

C.examining differences

D.following the time order

单项选择题