高压断路器额定工作电压是指断路器工作中的最高电压。（）

一个交流电压的瞬时值表达式为u=15sin100πt V，将该交流电加在一电阻上时，产生的电功率为25 W，那么这个电阻的阻值为___________Ω.

(18分)读“成渝经济开发区发展规划图”和“美国东北地区示意图”，回答下列问题。

(1)成渝经济开发区发展规划中，与北部产业发展带相比，南部产业发展带的城市分布特点和优势分别是什么?(6分)

(2)成渝经济开发区和美国东北部地区都具有发展工业优势，试分析共同的区位条件。(6分)

(3)试比较成都平原与美国东北部农业生产的差别。(6分)

Dear Economist,

My newly-wedded wife and I are deeply in love．There is, however, one issue that threatens the happiness of our marriage．I absolutely insist on shopping at Walmart．My wife, meanwhile, would rather avoid Walmart at all costs．

　　I have recently tried to convince her that not only does Walmart offer the lowest prices known to man, but that the chain is also a force for good―lower prices mean better standards of living for all consumers, increased global trade means a tighter-knit(紧密团结的) international community, and efficient operations translate into higher productivity growth for the economy．My wife complains about poor labour policies, the “fact” that Walmart squeezes suppliers, and that it puts local shops out of business．

　　Who is right? Will our marriage survive?

Brian Gee

Dear Brian,

I have to agree with you about Walmart．Jason Furman, then an economist at New York University, now an adviser to President Obama, famously argued in 2005 that Walmart was unwittingly (不知不觉地) a progressive success story．The chain’s prices don’t much affect me (I prefer Whole Foods) but Furman estimated that they benefited low-and-middle-income Americans to the sum of around $250 billion a year．

　　Walmart does not pay much, so it may depress wages．Then again, it may increase wages by offering jobs to the otherwise-unemployed．Either way, the benefits of low prices to Walmart shoppers far outweigh any seemingly reasonable costs to Walmart employees．And while it is true that Walmart employees tend to be poor, the same is true of Walmart shoppers．

　　Armed with this information you can face your wife with confidence．You are sure to win the conversation．The divorce is likely to be more argued．

Economist

小题1:What concerns Brian Gee so much that he wrote the letter?

A．His wife refuses to shop at Walmart．

B．They are faced with a divorce．

C．They can’t afford the costs of shopping at Walmart．

D．They are in conflict about shopping at Walmart．小题2:Brian Gee’s wife tends to hold the opinion that _________．

A．it is wrong for Walmart to depress its employees’ wages

B．consumers’ lives have improved thanks to Walmart

C．Walmart’s business operation increases productivity in economy

D．Walmart’s business increases global trade小题3:What can be inferred from the reply letter?

A．Some employees accept the low pay to keep the job．

B．Walmart appeals to only poor consumers and poor employees．

C．Employees suffer from Walmart’s low prices more than consumers．

D．Jason Furman, a New York University economist, spoke highly of Walmart．

一氧化碳是一种无色、无味、无嗅的气体，当浓度达到（）时能爆炸，有强烈的毒性。

A.5%-15%

B.10%-35%

C.13%-75%

正常心电图心房激动产生的波是()。

A．P波

B．Q波

C．R波

D．T波

E．U波