试题与答案

关于作用力与反作用力做功的关系,下列说法正确的是[ ] A.当作用力做正功时,反

题型:不定项选择

题目:

关于作用力与反作用力做功的关系,下列说法正确的是[ ]

A.当作用力做正功时,反作用力一定做负功

B.当作用力不做功时,反作用力也不做功

C.作用力与反作用力所做的功一定是大小相等、正负相反

D.作用力做正功时,反作用力也可以做正功

答案:

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参考答案:B解析: 需要李思解释的是:为什么拥有一身漂亮羽毛的雄孔雀能在求偶中具有竞争的优势这也就是需要解释:为什么雌孔雀更愿意与拥有漂亮羽毛的雄孔雀为偶因此,李思应答中的漏洞是:把所要解释的现象本...

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题型:阅读理解

阅读理解。

     Olaf Stapledon wrote a book called First and Last Men. in which he looked millions of years ahead. He

told of different men and of strange civilisations (文明), broken up by long 'dark ages' in between. In his

view, what is called the present time is no more than a moment in human history and we are just the First

Men. In 2,000 million years from now there will be the Eighteenth or Last Men.   

     However, most of our ideas about the future are really very short-sighted. Perhaps we can see some

possibilities for the next fifty years. But the next hundred? The next thousand? The next million? That's much

more difficult.   

     When men and women lived by hunting 50,000 years ago, how could they even begin to picture modern

life? Yet to men of 50,000 years from now, we may seem as primitive (原始的) in our ideas as the Stone-Age

hunters do to us. Perhaps through the cribe, These words, which I have just made up, have to stand for things

and ideas that we simply can't think of.   

     So why bother even to try imagining life far in the future? Here are two reasons. First unless we remember

how short our own lives are compared with the whole human history, we are likely to think our own interests

are much more important than they really are. If we make the earth a poor place to live because. we are

careless or greedy (贪婪) or quarrelsome. our grand-children will not bother to think of excuses for us.   

     Second, by trying to escape from present interests and imagine life far in the future, we may arrive at quite

fresh ideas that we can use ourselves. For example, if we imagine that in the future men may give up farming,

we can think of trying it now. So set you imagination free when you think about the future.

1. A particular mention made of Stapledon's book in the opening paragraph _______.  

A. serves as a description of human history   

B. serves an introduction to the discussion   

C. shows a disagreement of views   

D. Shows the popularity of the book

2. The text discusses men and women 50,000 years ago and 50,000 years from now

in order to show that ______.   

A. human history is extremely long   

B. life has changed a great deal   

C. it is useless to plan for the next 50 years   

D. it is difficult to tell what will happen in the future

3. Spundels and ballalators are used in the text to refer to _______.   

A. tools used in farming

B. ideas about modern life   

C. unknown things in the future

D. hunting skills in the Stone Age

4. According to the writer of the text, imagining the future will _______.   

A. serve the interests of the present and future generations   

B. enable us to better understand human history   

C. help us to improve farming   

D. make life worth living

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