患者男，72岁。寒战、高热、咳嗽、脓痰1周，阻塞性肺气肿病史20年，血气分析：PaO

下列命题的逆命题为真命题的是   [ ]

A.如果a=b，那么a²=b²      

B.平行四边形是中心对称图形    

C.两组对角分别相等的四边形是平行四边形    

D.内错角相等

Using this kind of hybrid, farmers are producing harvests _____ before. [ ]

A. twice as many as

B. twice as large as

C. as twice large as

D. as twice many as

据航天专家介绍，“神七”与“神六”最大的不同就是增加了出舱活动，包括行走、操作、安装设备等项目，均是为今后建立太空空间站作准备．请问下列哪项不是宇航员必须携带的维持生命的物质（　　）

A．鲜花

B．淡水

C．营养物质

D．氧气

当第三方在加油站打架时，应（）。

A、向公司说明，请求保安处理

B、立即报警

C、强制其离开

D、以暴制暴

阅读理解

     The Internet will open up new vistas (前景), create the global village-you can make new friends all

around the world.That, at least, is what it promised us.The difficulty is that it did not take the human mind

into account.The reality is that we cannot keep relationships with more than a limited number of people.

No matter how hard the Internet tries to put you in communication, its best efforts will be defeated by

your mind.

     The problem is twofold (双重的). First, there is a limit on the number of people we can hold in mind

and have a meaningful relationship with.That number is about 150 and is set by the size of our brain

.Second, the quality of your relationships depends on the amount of time you invest (投入) in them.We

invest a lot in a small number of people and then distribute what's left among as many others as we can.

The problem is that if we invest little time in a person, our engagement with that person will decline (减弱)

until eventually it dies into "someone I once knew".

     This is not, of course, to say that the Internet doesn't serve a socially valuable function.Of course it

does.But the question is not that it allows you to increase the size of your social circle to include the rest

of the world, but that you can keep your relationships with your existing friends going even though you

have to move to the other side of the world.

     In one sense, that's a good thing.But it also has a disadvantage.If you continue to invest in your old

friends even though you can no longer see them, then certainly you aren't using your time to make new

friends where you now live.And I suspect that probably isn't the best use of your time.Meaningful

relationships are about being able to communicate with each other, face to face.The Internet will slow

down the rate with which relationships end, but it won't stop that happening eventually.

1. What is stressed in the first paragraph?

A. The present situation of the Internet.

B. The difficulty in communication on the Internet.

C. The socially valuable function of the Internet.

D. The role of the human mind in the Internet communication.

2. The underlined word "engagement" in the second paragraph probably means" ________ ".

A. appointment  

B. connection

C. interview  

D. agreement

3. According to the passage, the author holds the view that ______.

A. the Internet fails to play so valuable a role in communication as it promised

B. the Internet determines the quality of social relationships

C. the Internet greatly increases the size of social circles

D. the Internet communication is no less effective than the facetoface talk

4. What is the author's attitude towards the use of the Internet to strengthen relationships?

A. He is uncertain about it.  

B. He is hopeful of it.

C. He approves of it.  

D. He doubts it.