问题 选择题

冬冬在实验室做铁丝在氧气中燃烧的实验时,没有观察到剧烈燃烧,火星四射的现象.你认为下列不属于该实验失败的主要原因是(  )

A.氧气不纯

B.集气瓶没预先装少量水

C.铁丝太粗

D.系在铁丝上的火柴燃烧尽了,才将铁丝伸入集气瓶

答案

没有观察到火星四射,说明没有燃烧现象,也是就没有发生铁丝的燃烧,故所有分析可围绕燃烧来进行,更确切地说是铁丝的燃烧条件来进行.燃烧需要可燃物与氧气有一定的接触,且接触越充分越容易燃烧,氧气的浓度越大越易燃烧,温度越高燃烧也易发生;

A、收集到的氧气纯度太低时,铁丝可能不燃烧,故不符合题意;

B、集气瓶底部预先放入水的目的是为了防止生成物溅落炸裂集气瓶的,与铁丝是否能够燃烧无关,符合题意;

C、铁丝太粗,与氧气接触不充分,铁丝可能不燃烧,故不符合题意;

D、待铁丝上的火柴燃烧尽了,才将铁丝伸入集气瓶,铁丝的温度未达到着火点,铁丝不燃烧,故不符合题意;

故选B.

阅读理解

阅读理解

     Americans are thinking about national education standards recently developed by teachers and other

education experts. The National Governors Association (NGA) and the Council of Chief State School

Officers (CCSSO) led the effort.

     The United States, unlike other nations, has never had the same school standards across the country. What is the reason? Education is not discussed in the Constitution.  That document limits the

responsibilities of the federal government. Other responsibilites,     like education, fall to each state.

     Local control of education probably was a good idea two hundred years ago. People stayed in the

same place and schools knew what students needed to learn. But today, people move to different  cities.

And some people work at jobs that did not exist even twenty years ago.

     Many American educators say that getting a good education should not depend on where you live.

They say that some states have lowered their standards in order to increase student scores on tests

required by the No Child Left behind Act.

     Kara Schlosser is communications director for the CCSSO. She says the new standards clearly state

what a student should be able to do to be successful in college and work.

     Forty--eight states have a1ready shown approval for the standards. Two states refuse to accept the

idea. Critics say that working toward the same standards in every state will not guarantee excellence for

all. Some educators in Massachusetts say adopting the national standards will hurt their students because

the state standards are even higher. Others say the change will be too costly, requiring new textbooks

and different kinds of training for teachers. Still others fear federal control.

     Supporters say the standards are goals and do not tell states or teachers how to teach. They also say

the federal government is not forcing acceptance. However, approving the standards will help states

qualify (取得资格)for some federal grant money.

1. What would be the best title for the passage?

A. Local Control of Education Standards out of Date

B. American National Education Standards under Consideration

C. Education Standards in Each State--Good or Bad.

D. Acceptance of the New Standards in the United States

2. Why is local control of education no 1onger a good idea today?

A. Because local standards are limited.

B. Because it is required by the federal government.

C. Because people today moves among states more often than before.

D. Because America has never had the same school standards throughout the  country.

3. Some people are against the nationa1 education standards because__________

A. the standards are higher than those of each state

B. they are not yet prepared for the new standards

C. the standards may prevent some students gaining excellence

D. they don't want the federal government to train their teachers

4. If a state agrees to accept the national standards, it will probably get ________.

A. more students      

B. advice on how to improve teaching

C. better textbooks    

D. money from the federal government

单项选择题