问题 单项选择题

以下关于病毒的描述中,不正确的说法是______。

A.对于病毒,最好的方法是采取“预防为主”的方针

B.杀毒软件可以抵御或清除所有病毒

C.恶意传播计算机病毒可能会是犯罪

D.计算机病毒都是人为制造的

答案

参考答案:B

解析: 杀毒软件并不能查杀任何毒,它需要不断的升级,下载新的反病毒数据包以提升查杀病毒的能力。

问答题

已知Cl2和碱溶液在不同条件下,得到的产物不同.某兴趣小组用图甲装置制取氯酸钾、次氯酸钠和探究氯水的性质.(3Cl2+6KOH

加热
.
KClO3+5KCl+3H2O)

图甲中:A为氯气发生装置;B的试管里盛有15mL 30% KOH溶液,并置于水浴中;C的试管里盛有15mL 8% NaOH溶液,并置于冰水浴中;D的试管里加有紫色石蕊试液.

请填写下列空白:

(1)制取氯气时,在圆底烧瓶里加入一定质量的二氧化锰,通过______(填仪器名称)向圆底烧瓶中加入适量的浓盐酸.装置A中反应的离子方程式为______.需要向烧瓶中加碎瓷片吗?______(选填:“需要”、“不需要”).

(2)反应结束后,烧瓶里的溶液______.

A.一定显酸性B.可能显酸性,也可能为中性C.只有氧化性

D.只有还原性E.既有氧化性又有还原性

(3)反应完毕,B试管中有少量晶体析出,经冷却后,有大量晶体析出.图乙中符合该晶体溶解度曲线的是______(填编号字母);从B的试管中分离出该晶体必须用到的玻璃仪器有______.

(4)该小组同学发现制得的氯酸钾产量偏低,可能的一种原因是Cl2中含有HCl气体.对此问题可以通过改进实验装置的方法进行避免.方法是______.

(5)实验中可观察到D的试管里溶液的颜色由紫色先变为______色,最终变为______色.

(6)C装置中反应完毕的现象是______.

(7)请在装置图甲方框中画出缺少的实验装置,并注明试剂.

阅读理解

In our life, we have rarely expressed our gratitude to the one who'd lived those years with us.In fact, we don't have to wait for anniversaries to thank the ones close to us —the ones so easily overlooked.If I have learned anything about giving thanks, it is this: give it now! While your feeling of appreciation is alive and sincere, act on it.Saying thanks is such an easy way to add to the world's happiness.

Saying thanks not only brightens someone else's world, it brightens yours.If you're feeling left out, unloved or unappreciated, try reaching out to others.It may be just the medicine you need.

Of course, there are times when you can't express gratitude immediately.In that case don't let embarrassment sink you into silence —speak up the first time you have the chance.

Once a young minister.Mark Brian, was sent to a remote parish of Kwakiuti Indians in British Columbia.The Indians, he had been told, did not have a word for thank you.But Brian soon found that these people had exceptional generosity.Instead of saying thanks, it is their custom to return every favor with a favor of their own, and every kindness with an equal or superior kindness.They do their thanks.

I wonder if we had no words in our vocabulary for thank you, would we do a better job of communicating our gratitude? Would we be more responsive, more sensitive, more caring?

Thankfulness sets in motion a chain reaction that transforms people all around us—including ourselves.For no one ever misunderstands the melody of a grateful heart.Its message is universal; its lyrics transcend (超越) all earthly barriers; its music touches the heavens.

53.In the first paragraph the writer mainly encourages us      .

A.never to overlook our close friends in daily life

B.to express our sincere thanks timely to those around us

C.to wait for a proper occasion to show our thanks

D.to increase the world's happiness by saying thanks

54.According to the writer,      could be the best way to prevent ourselves from being left out.

A.seeing a doctor to find the right medicine we need

B.expressing our thanks as much as we can

C.showing others actively we are interested in them

D.speaking up the moment we have the chance

55.Mark Brian's story is mentioned in the passage in order to show the fact that       .

A.the Indians didn't have any words for appreciation

B.the Indians were particularly generous to others

C.Mark Brian's set the Indians an example to show thanks

D.some people may express their thanks through different approaches

56.What message does the writer intend to communicate in the last paragraph?

A.Thanks is of great importance in developing harmonious relationship.

B.One grateful heart is surely to deserve another good one in return.

C.Thankfulness which goes beyond all barriers is universally understood.

D.Human beings would misunderstand each other without appreciation.