缓慢性心律失常的机制：①（）；②（）。

阅读短文，选择正确答案。

      Many Americans have been leaving their cars at home and riding to work on bicycles. Andy Clark is the

leader of the League of American Bicyclists. His group supports bicycling for fun, fitness and transportation.

      Clark says this is good news for the environment. He says riding a bicycle to work does not burn fossil

fuel or creates dangerous pollutions. Experts say the effects are the most important on short trips. The

Department of Transportation says fifty percent of Americans drive eight kilometers or fewer to work. Shorter

car trips set out more pollution into the air for each kilometer drive. This is because the car engine will set out

the harmful air when it warms up before it can work well. 

      James, a members of Congress (国会), is a strong supporter of bicycle use. He says cities, counties, state

governments and state highway transportation agencies are planning the roadways of the future. They are

creating roads and paths for bicycles in cities and between communities.

      Last year, Portland, the Pacific Northwest city in the state of Oregon, had the highest percentage of bicycle

users in the United States. Portland has been doing progressive city planning for many years to create special

paths for bike riders. 

1. What happened in America now according to the news? [ ]

A. Many Americans lost jobs now.

B. Many Americans prefer short trips.

C. There are more and more bicyclists now in America.

D. The pollution is getting worse and worse in America.

2. Where is Portland? [ ]

A. One of the cities in the USA.

B. One of the counties in the USA.

C. One of the states in the USA.

D. A country in the northwest of the USA.

3. What does the underlined word "harmful" mean in the second paragraph? The closest meaning is "_______". [ ]

A. polluted

B. dangerous

C. clean

D. foolish

4. What is the main idea of the passage? [ ]

A. Many Americans like bike-riding for fun.

B. Short car trips can reduce pollution.

C. American government suggests people riding bicycles.

D. Many Americans ride bicycles to support environment protection.

5. Where can we read it possibly? [ ]

A. From a website.

B. From a poster.

C. From a newspaper.

D. From an advertisement.

“支配物理世界之运动的必然性，也支配着精神世界的运动，因而在这个世界中，一切都服从于注定的命运”。这种观点( )

A．对必然性作用的科学揭示

B．会导致“宿命论”

C．会导致唯意志论

D．揭示了必然性的本质

关于WINDOWS操作系统的特点，以下说法错误的是（）。

A.各种版本的Windows操作系统中，最新的版本是Vista

B.WindowsXP在设备管理方面可支持“即插即用”

C.WindowsXP支持的内存容量可超过1GB

D.Windows系统主要的问题是可靠性和安全性还不理想

(12分)【国家和国际组织常识】

2011年1月18日，美国佛罗里达州向联邦法院递交了反对奥巴马总统已经签署的《医疗改革法案》议案，至此，全美共有26个州提起诉讼，成为美国历史上对联邦权威最大的一次挑战。1月19日，共和党占优势的美国国会众议院通过了废除美国总统奥巴马医改法的议案。

(1)材料体现了美国三权分立的权力运行方式，请问美国三权分立原则的核心内容是什么?(4分)

(2)如果以“三权分立在美国”为题写一篇时政论文，请列出要点。(8分)

简述知识经济、特征、知识经济与教育的关系、对策