问题 解答题

某工厂用7万元钱购买了一台新机器,运输安装费用2千元,每年投保、动力消耗的费用也为2千元,每年的保养、维修、更换易损零件的费用逐年增加,第一年为2千元,第二年为3千元,第三年为4千元,以此类推,即每年增加1千元。问这台机器最佳使用年限是多少年?(年平均费用最低时为最佳使用年限),并求出平均费用的最小值。

答案

解:设这台机器最佳使用年限是n年,

则n年的保养、维修、更换易损零件的总费用(万元)为

n年的投保、动力消耗的费用(万元)为:0.2n,

∴总费用为7+0.2+0.2n+=7.2+

∴n年的年平均费用为

等号当且仅当,即n=12时成立,

所以,这台机器最佳使用年限是12年,年平均费用的最小值为1.55万元.

阅读理解

阅读理解。

     It is true that good writers rewrite and rewrite and then rewrite some more. But in order to work up

the desire to rewrite, it is important to learn to like what you write at the early stage.

     I am surprised at the number of famous writers I know who say that they so dislike reading their own

writing later that they even hate to look over the publishers' opinions. One reason we may dislike reading

our own work is that we're often disappointed that the rich ideas in our minds seem very thin and plain

when first written down. Jerry Fodor and Steven Pinker suggest that this fact may be a result of how our

minds work.

     Different from popular belief, we do not usually think in the words and sentences of ordinary language

but in symbols for ideas (known as'mentalese'),and writing our ideas down is an act of translation from

that symbolic language. But while mentalese contains our thoughts in the form of a complex tapestry (织锦),writing can only be composed one thread at a time. Therefore it should not be surprising that our first

attempt at expressing ideas should look so simple. It is only by repeatedly rewriting that we produce new

threads and connect them to get closer to the ideas formed in our minds.

     When people write as if some strict critics (批评家) are looking over their shoulder, they are so

worried about what this critic might say that they get stuck before they even start. Peter Elbow makes an

excellent suggestion to deal with this problem. When writing we should have two different minds. At the

first stage, we should see every idea, as well as the words we use to express it, as wonderful and worth

putting down. It is only during rewrites that we should examine what we excitedly wrote in the first stage

and check for weaknesses.

1. What do we learn from the text about those famous writers?

A. They often regret writing poor works.

B. Some of them write surprisingly much.

C. Many of them hate reading their own works.

D. They are happy to review the publishers' opinions.

2. What do people generally believe about the way human minds work?

A. People think in words and sentences.

B. Human ideas are translated into symbols.

C. People think by connecting threads of ideas.

D. Human thoughts are expressed through pictures.

3. What can we conclude from the text?

A. Most people believe we think in symbols.

B. Loving our own writing is scientifically reasonable.

C. The writers and critics can never reach an agreement.

D. Thinking and writing are different stages of mind at work.

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