在大型建设工程项目中，信息交流的问题导致工程变更和工程实施的错误约占工程总成本的(

分解因式手x⁶-手手^o的结果是（　　）

A．3（x+y²）（x-y²）

B．3（x+y²）（x+y）（x-y）

C．3（x-y²）²

D．3（x-y）²（x+y）²

亚急性甲状腺炎多见于下列人群中的（）

A.儿童

B.青春期女性

C.40～50岁女性

D.50～60岁女性

E.老人

案例摘要：患者，男性，60岁。有肺源性心脏病病史2年，3天前受凉后出现发热、咳嗽加重，咳黄色痰，并出现呼吸困难不能平卧。查体双肺散在多发干湿性啰音，心率120次/分，下肢水肿。

既可用于心源性哮喘，又可用于支气管哮喘的平喘药是（）

A.肾上腺素

B.吗啡

C.异丙肾上腺素

D.特布他林

E.氨茶碱

阅读理解。

    It was the summer of 1965. DeLuca, then 17, visited Peter Buck, a family friend. Buck asked

DeLuca about his plans for the future. "I'm going to college, but I need a way to pay for it," DeLuca

recalls saying. "Buck said, 'You should open a sandwich shop.'"

    That afternoon, they agreed to be partners. And they set a goal: to open 32 stores in ten years.

After doing some research, Buck wrote a check for $1000. DeLuca rented a storefront (店面) in

Connecticut, and when they couldn't cover their start-up costs, Buck kicked in another $1000.

    But business didn't go smoothly as they expected. DeLuca says, "After six months, we were doing

poorly, but we didn't know how badly, because we didn't have any financial controls." All he and Buck

knew was that their sales were lower than their costs.

    DeLuca was managing the store and going to the University of Bridgeport at the same time. Buck

was working at his day job as a nuclear physicist in New York. They'd meet Monday evenings and

brainstorm ideas for keeping the business running. "We convinced ourselves to open a second store.

We figured we could tell the public, 'We are so successful, we are opening a second store." And they

did-in the spring of 1966. Still, it was a lot of learning by trial and error.

    But the partners' learn-as-you-go approach turned out to be their greatest strength. Every Friday,

DeLuca would drive around and hand-deliver the checks to pay their suppliers. "It probably took me

two and a half hours and it wasn't necessary, but as a result, the suppliers got to know me very well,

and the personal relationships established really helped out," DeLuca says.

    And having a goal was also important. "There are so many problems that can get you down. You

just have to keep working toward your goal," DeLuca adds.

    DeLuca ended up founding Subway Sandwich, the multimillion-dollar restaurant chain.

1. DeLuca opened the first sandwich shop in order to ____.

A. support his family

B. pay for his college education

C. help his partner expand business

D. do some research    

2. Which of the following is true of Buck?

A. He put money into the sandwich business.

B. He was a professor of business administration.

C. He was studying at the University of Bridgeport.

D. He rented a storefront for DeLuca. 

3. What can we learn about their first shop?

A. It stood at an unfavorable place.

B. It lowered the prices to promote sales.

C. It made no profits due to poor management

D. It lacked control over the quality of sandwiches   

4. They decided to open a second store because they ___.

A. had enough money to do it.

B. had succeeded in their business

C. wished to meet the increasing demand of customers

D. wanted to make people believe that they were successful  

5. What contribute most to their success according to the author?

A. Learning by trial and error.

B. Making friends with suppliers.

C. Finding a good partner.

D. Opening chain stores

2C510、2C540电机的防爆类型为（）

A、隔爆型

B、增安型

C、本安型

D、正压通风型