某溶液中可能含有OH—、CO32—、AlO2—、SiO32—、SO42—、HCO

发布时间：2017-05-01 12:09 │ 来源：www.tikuol.com

题型：选择题

问题：

某溶液中可能含有OH^—、CO₃^2—、AlO₂^—、SiO₃^2—、SO₄^2—、HCO₃^—、Na⁺、Fe³⁺、Mg²⁺、

Al³⁺等离子。当向该溶液中逐滴加入一定物质的量浓度的盐酸溶液时，发现生成沉淀的物质的量随盐酸溶液的体积变化的图像如下图所示。下列说法正确的是（）

A．原溶液中一定含有的阴离子是：OH^—、SiO₃^2—、AlO₂^—、CO₃^2—

B．反应最后形成的溶液中的溶质为NaCl

C．原溶液中一定含有Na₂SO₄

D．原溶液中含有CO₃^2-与AlO₂^-的物质的量之比为1∶2

考点：离子共存

题型：选择题

鸡蛋壳的主要成分是碳酸钙，为了测定某鸡蛋壳中碳酸钙的质量分数，小芳同学进行了如下实验，将鸡蛋壳洗净、干燥并捣碎后，称取10.0g放在烧杯里，然后往烧杯中加入足量地方的稀盐酸，待完全反应（杂质不反应）不再有气泡产生时，测得生成二氧化碳气体的质量为3.3g，计算该鸡蛋壳中碳酸钙的质量分数．

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阅读理解。

     Many people think it is safe to use a cell phone while they are driving. Yet Scores of studies
suggest that real multitaskers - those who can carry out multiple (多个的) tasks equally well,
make up just 2 per cent of the population. More surprisingly, the so-called "supertaskers" actually
have differently structured brains to the other 98 percent.
     The brain areas that make supertaskers differ from the rest of the population are the same parts
that are most different between humans and nonhuman primates (灵长类), according to David
Strayer, director of the applied cognition lab at the University of Utah. Scientists are unsure of the
reason why some brains are different. In fact, we could all benefit from doing just one task at once.
     In most of us, scientists have located a "bottleneck in the brain" that may explain why we find it
hard to do two things at once.
     The problem appears to be caused by a logjam of nerve messages. Faced with two almost
simultaneous (同时的) tasks less than 300 milliseconds apart, the brain's ability to deal with the
second one slows down. The neural (神经的) response to the second task was postponed until
the response to the first was completed. This means that with e-mails, phone calls, text messages
and online social media all competing for our attention, often against a background of television,
radio or music, our brains can reach information overload.
     Scientists made the discovery after scanning the brains of volunteers attempting to multitask on
a computer. The task was deliberately designed to involve the use of different senses and motor
responses.
     Dr Rene Marois, one of the neuroscientists who carried out the experiment at Vanderbilt University
in Nashville, Tennessee, said: "Our research offers neurological evidence that the brain cannot
effectively do two things at once." The next step, the neuroscientists say, is finding out "why these
areas cannot process two tasks at once."

1. How many people can drive equally well while using a cell phone?

A. Nobody.
B. Everybody.
C. 2 in 100.
D. 98 in 100.

2. The researchers tried to find out the difference between _____ brain structures.

A. different supertaskers'
B. supertaskers' and ordinary people's
C. humans' and nonhuman primates'
D. supertaskers' and nonhuman primates'

3. We can infer from the article that the brain takes 300 milliseconds to _____.

A. make a neural response
B. get ready for a response
C. complete a task
D. finish two tasks

4. If we _____, our brains may reach information overload.

A. serf the Internet after listening to music
B. use a cell phone against a background of television
C. complete all kinds of tasks within the same day
D. have lots of tasks queuing for responses

5. From the dictionary explanations, choose one for the underlined word "motor" in Paragraph 5.

A. having an engine
B. relating to vehicles with engines
C. relating to nerves that make muscles move (control body movement)
D. the part of a machine that makes it move

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法定存款准备率

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国务院制定颁布的卫生规范性文件是（）
国务院卫生行政部门颁布的卫生规范性文件是（）

A.地方性卫生法规

B.卫生基本法律

C.卫生法律

D.卫生行政规章

E.卫生行政法规

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实务中，对初次投保健康保险的被保险人都要规定（）。

A.免责期

B.观察期

C.等待期

D.加费额

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