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问题 选择题

如图所示是空间某一电场中的一条电场线．M、N是该电场线上的两点．下列说法中正确的是

（　　）

A．该电场一定是匀强电场

B．比较M、N两点的场强大小，一定有EM＞EN

C．比较M、N两点的电势，一定有φM＞φN

D．比较电子在M、N两点的电势能，一定有EM＞EN

答案

A、一条电场线无法确定场强大小和方向是否处处相同，所以该电场不一定是匀强电场．故A错误．

B、电场线的疏密才反映电场强度的大小，而一条电场线无法确定疏密，所以不能比较M、N两点的场强大小．故B错误．

C、根据顺着电场线方向电势降低，一定有φN＞φM．故C错误．

D、若电子从M运动到N，电场力对电子做正功，电势能减小，则一定有EM＞EN．故D正确．

故选D

写作题

阅读下面短文，然后按要求写一篇150词左右的英语短文。

The officials in the White House and CIA (中央情报局)are rejecting Edward Snowden's beg for mercy. “Mr. Snowden has been against the U.S. law,” White House adviser Dan Pfeiffer said on Sunday about the former systems analyst who has turned fugitive (逃亡者) in Russia. “He should return to the US and face the justice and judgment, and there is no possibility for mercy and forgiveness.”

However, many people support Snowden and a sociology professor Svallfors in Sweden has recommended Snowden for the Nobel Peace Prize for his “heroic effort at great personal cost” disclosing the spying conducted by the National Security Agency of United States. He wrote, “Because of his bravery, Snowden helped to make the world a little bit better and safer”.

It may be too late for Snowden to receive the award this year, but the nomination should be taken seriously by the Nobel Prize committee for next year’s prize. If Snowden is awarded the prize in 2014, he would be the youngest Nobel Peace Winner in the history of the prize.

【写作内容】

1.以约30词概括上文的主要内容。

2.以约120词发表你对“Information Security”的看法，内容包括：

(1)简述信息安全的重要性；

(2)请举例说明信息安全事故的危害；

(3)谈谈如何维护信息安全。

【写作要求】

1.作文中可以使用亲身经历或虚构的故事，也可以参照阅读材料的内容，但不得直接引用原文中的句子。

2.作文中不能出现真实姓名和学校名称。

【评分标准】

概括准确，语言规范，内容合适，语篇连贯。

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单项选择题

心血管系统各段管壁共有的成分为（）。

A.内皮

B.间皮

C.内弹性膜

D.外弹性膜

E.平滑肌
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