问题 填空题

砼动弹性模量试验是采用()来测定。

答案

参考答案:共振法

阅读理解

阅读理解。

     Students often want to practice their English outside class. One of the best ways to practice your English

is to speak to a foreigner. This week's question comes from a student who is eager to start a conversation

with the foreigners he sees every day. One student asks, "Is it Okay to try to talk to foreigners I see in the

street?"

     The answer is yes or no, but probably no! If you see a foreigner who looks lost, it is polite to ask him,

"May I help you?" But, otherwise, you should probably let them get on with their business. Situations,

however, do exist (存在) where it is quite all right to talk to foreigners. If a foreigner enters your school,

office, shop or restaurant, for instance (例如), feel free to ask him (for example): 

     — What is your name? 

     — Where do you come from? 

     — What do you think of Beijing? 

     — How long will you stay in Beijing?

     There are also situations where it's Okay to talk to foreigners in public places. If you see a foreigner

alone in a restaurant, bar or coffee shop, it may be appropriate (合适的) to ask him or her:

     — Is this seat free? 

     — Do you mind if I talk to you in English?

     You can probably help them if they are new to China and if they are alone. You may be able to make them

feel more welcome. 

     After a few such questions, you should know whether this person wants to talk to you or not. If they ask

you similar questions, or if they give long, informative answers, you're in luck. If not, then give them their

privacy (独处). Talking to strangers is fun if you choose the right time and place.

1. It is the best way to practice your spoken English with _____. [ ]

A. Japanese

B. Americans

C. your classmates

D. French people

2. From the second paragraph, we can get to know that _____. [ ]

A. it is polite to stop a foreigner to talk with him in the street

B. it is polite to interrupt foreigners in a conversation

C. it is impolite to interrupt a foreigner when he or she is on business

D. it is impolite to help a foreigner find his way

3. When you first meet a foreigner, you should say "_____". [ ]

A. Where are you going?

B. Have you eaten your dinner?

C. Can you help me with my English?

D. Nice to meet you.

4. The writer suggests us that we should _____. [ ]

A. follow the foreigners when we meet them in the street

B. talk with foreigners in an accepted way

C. have a meal with foreigners in a restaurant

D. move to a place where a foreigner lives

5. This passage comes from a newspaper in column _____. [ ]

A. Sports

B. Health

C. Language

D. Business

阅读理解与欣赏

  王安石曾赋诗咏梅:“遥知不是雪,为有暗香来。”在这里,当白梅和落雪引起人们视觉上的混淆时,发挥重要辨别作用的就是嗅觉。人类能够识别和记忆大约1万种不同的气味,其生理机制却一直是个谜。为此,许多科学家孜孜不倦地进行研究,以求找到解开奇妙的嗅觉世界之谜的钥匙。

  在嗅觉的早期研究中,气味的识别,一般被认为是气味分子与嗅觉受体相结合的结果。1977年,科学家发现这种受体存在于嗅觉神经元伸入鼻腔黏膜的嗅纤毛上。一旦将这些嗅纤毛移除,嗅觉能力也将随之丧失。这说明嗅纤毛是嗅觉系统运行的起点。

  但是,气味分子又是如何转化为嗅觉信号传递到大脑的呢?美国科学家理查德·阿克塞尔和琳达·巴克发现,当气味分子与嗅觉受体结合后,作为化学信号的气味分子经过属 于GTP蛋白(通称G蛋白)的嗅觉受体的复杂作用,转变为电信号后,便沿着嗅觉神经开始一场拉力跑。这些信号先从鼻腔进入颅内,最后被传至大脑嗅觉皮层某些精细区域,在那里它们被翻译成特定的嗅觉信息,即人们感知。这就是阿克塞尔和巴克为我们描述的完整的嗅觉信号通路理论。

  其实,在上世纪80年代末期,科学家就发现在探测气味的神经元中存在着一套G蛋白信号通路,而且前人的生物化学和生理学研究成果也暗示G蛋白可能参与了嗅觉信号的传导过程。当阿克塞尔和巴克在构建嗅觉信号通路理论时,他们发现嗅觉受体属于G蛋白受体家族,蒙在嗅觉系统这个谜团上的“盖头”终于被掀开了一角。

  作为优秀的科学家,阿克塞尔和巴克并没有在这里停下脚步。他们将嗅觉系统的研究提升到了分子水平,尤其是侧重基因方面的研究。他们认为人类能够识别众多气味分子,其自身必有多种能识别这些气味分子的属于G蛋白的嗅觉受体,并且还存在着编码这些蛋白的基因家族。阿克塞尔和巴克这种创造性的研究为他们2004年获得诺贝尔生理 学和医学奖奠定了基础。

1、下列对阿克塞尔和巴克的嗅觉信号通路理论理解错误的一项是

[ ]

A、气味分子在属于G蛋白的嗅觉受体的作用下从化学信号转变成为电信号。

B、嗅觉信号通路的末端是大脑嗅觉皮层中的某些精细区域。

C、嗅觉信号通路理论阐述的是气味分子转化为嗅觉信号传递到大脑的过程。

D、作为化学信号的气味分子到达大脑嗅觉皮层某些精细区域被翻译成嗅觉信息。

2、下列对文中嗅觉研究成果的承接顺序表述正确的一项是[ ]

A、在发现嗅纤毛是嗅觉系统运行的起点后,科学家进一步认识到气味的识别是气味分子与嗅觉受体相结合的结果。

B、在嗅觉信号通路理论提出后,科学家又发现了探测气味的神经元中存在着一套G蛋白信号通道。

C、在生物化学和生理学研究成果暗示G蛋白可能参与了嗅觉信号的传导后,科学家发现了在探测气味的神经元中有一套G蛋白通路。

D、在得知G蛋白可能参与嗅觉信号的传导过程后,科学家即确认嗅觉受体属于G蛋白受体家族。

3、根据原文提供的信息,以下推断正确的一项是[ ]

A、从2004年诺贝尔生理学和医学奖的评选可以看出,基因研究很有可能成为嗅觉系统研究的重要方面。 B、王安石的咏梅诗和阿克塞尔、巴克的嗅觉研究说明,中国人关注的是审美,外国人关注的是科学。

C、人类能够识别约1万种气味,按照阿克塞尔和巴克的理论,人类自身也应该有约1万种属于G蛋白的嗅觉受体。

D、嗅觉研究的历史说明,科学研究应该继承前人的研究成果,沿袭前人的研究方向和研究方法,这样都能取得进展。

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