当导线的应力增大时,下列哪种情况正确() A.弧垂增大 B.弧垂变小 C.档距变小

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问题:

当导线的应力增大时,下列哪种情况正确()

A.弧垂增大

B.弧垂变小

C.档距变小

D.档距增大

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题型:单项选择题

阅读理解。

     In your school bags, you may have a pencil, some kinds of pens, a ruler, and some books. None of

these things grow in the fields. They were all made  in  factories. And, of course, they were invented by

some people. There have not always been pencils or pens, a  ruler and books. Thousands of years ago

no one knew about these things.

     Who invented them first? How did they have such clever ideas? We always don't know. There have

been many thousands of inventions, large and small, in the human history. Some of these inventions have

changed the world. Such as paper, printing, radio, telephone and computer, and we know the inventors.

But we have forgotten most of the other inventors.

     Who invented the clock, for example,  or  the lock to the  door?  We don't know. There have been

thousands of inventors and we should grateful (感激的) to  them  for their clever ideas. Will you be one

of them when you grow up?

1. Most things in your school bags are made of _________.

A. paper            

B. wood            

C. metal            

D. nylon

2. The inventors invented these things because _________.  

A. their children were at school                  

B. they hoped to save some money

C. they have a lot of clever ideas                

D. they have good machines 

3. The history books tell us _________.

    

A. who invented paper and printing              

B. who invented clocks and doors

C. when the first key was invented                

D. how much the silk cost 

4. We don't know ________.

A.the names of the inventors of paper          

B. the names of the inventors of telephone

C. the names of the inventors of lamp            

D. the names of most inventors 

5. The writer wonders _________.

A. if you are an inventor                        

B. if you want to be an inventor

C. what's invented by you                        

D. how many inventors you know

题型:单项选择题

“普天之下,抟心揖志,器械一量,书同文字。”——(秦)《琅邪台刻石》其中的文字应该是()

A.小篆

B.隶书

C.楷书

D.行书

题型:单项选择题

在国际工程建设程序中,招标和投标工作处于工程项目()阶段。

A.前期准备 

B.实施 

C.决策 

D.可行性研究

题型:单项选择题

重大质量事故由( )归口管理。

A.国务院

B.建设部

C.省、自治区、直辖市建设行政主管部门

D.市县级建设行政主管部门

题型:单项选择题

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