单向板的受力特点是板上荷载( )。A．主要沿短边方向传递到支撑结构 B．主要沿长边

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。

氨茶碱松弛支气管平滑肌的原因可能包括（）

A.抑制磷酸二酯酶，使cAMP含量增加

B.阻断腺苷受体

C.抑制过敏性介质释放

D.降低细胞内钙

E.阻断支气管平滑肌的Mi胆碱受体

阅读理解

       Keeping a full social calendar may help protect you from dementia (痴呆),researchers said on

Monday.Socially active people who were not easily stressed had a 50 percent lower risk of developing

dementia compared with men and women who were isolated and prone to distress,they reported in the

journal Neurology.

      "In the past,studies have shown that chronic distress (长期抑郁) can affect parts of the brain,possibly

leading to dementia," HuiXin Wang of the Karolinska Institute in Sweden,who led the study,said in a

statement."But our findings suggest that having a calm and outgoing personality in combination with a

socially active lifestyle may decrease the risk of developing dementia even further."

       An estimated 24 million people worldwide have memory loss,problems with direction and other

symptoms that signal Alzheimer's disease and other forms of dementia.Researchers believe the number of

people with dementia may quadruple (变为四倍) by 2050,underlining the importance of better

understanding the condition.

       The Swedish study involved 506 elderly people who did not have dementia when first examined.The

volunteers were given questionnaires about their personality traits and lifestyles and then tracked for six

years.Over that time,144 people developed dementia with more socially active and less stressed men and women 50 percent less likely to be diagnosed with the condition.

     "The good news is,lifestyle factors can be modified as opposed to genetic factors which cannot be

controlled," Wang said."But these are early results,so how exactly mental attitude influences risk for

dementia is not clear."

1．Study suggests that________.

A．women have a 50 percent lower risk of developing dementia than men

B．50 percent of elderly people have the risk of developing dementia

C．people with active lifestyles will never develop dementia

D．going to a party will cut the risk of developing dementia

2．________people are believed to develop dementia in one year on average in the future 40 years.

A．About 1.8 million 

B．About 24 million

C．About 72 million 

D．About 96 million

3．It can be inferred that________could be a good way to decrease the risk of developing dementia.

A．living alone in a deserted island

B．modifying genetic factors

C．changing lifestyles

D．getting away from activities

4．Which of the following is TRUE according to the passage?

A．It is not clear whether mental attitude influences the risk of developing dementia.

B．The people involved in the Swedish study are never diagnosed with dementia.

C．Memory loss,direction confusion could be the symptoms of dementia.

D．The number of people with calm and outgoing personality is growing.

关于物业服务合同的说法，错误的是( )。

A．物业服务合同是平等主体之间成立的民事合同

B．物业服务合同是合同法中15种有名合同之一

C．不能将物业服务合同归属于合同法中的委托合同

D．物业服务合同是整个物业管理关系的核心

关于C++主函数特性，下列叙述正确的是( )。

A．主函数在同一个C++文件中可以有两个
B．主函数类型必须是void类型
C．主函数一定有返回值
D．每个C++程序都必须有一个main()函数

高压厂用母线为何装设低电压保护？