问题 选择题

某同学按图示电路连接实物后闭合开关,发现电灯不亮.他将高阻值的电压表并联在A、C之间时,电压表的读数为U;将该表并联在A、B之间时,电压表的读数为U;将该表并联在B、C之间时,电压表的读数为零.则故障可能是(  )

A.AB段断路

B.BC段断路

C.AB段短路

D.无法判断

答案

A、若AB段断路时,电路中电流为零,根据欧姆定律可知,灯L的电压为零,A、B两端的电压等于电源两端的电压U,与题干提供的信息相符.故A正确.

    B、若BC段断路时,电路中电流为零,根据欧姆定律可知,电阻R的电压为零,BC两端的电压等于电源两端的电压U,与题干提供的信息不相符.故B错误.

    C、若AB段短路时,电路中电流增大,电灯变亮,与题信息不符.故C错误.

    D、由上可知D错误.

故选A

单项选择题
阅读理解

Standardized exam in American public education are being reformed. Over the next four years, hundreds of university professors and testing experts will work together to design new assessment system.

The new tests will be computer-based and will measure higher-order skills ignored by the multiple-choice exams used in all states,including students’ ability to read complex texts, synthesize(合成)information and do research projects.

Because the new tests will be computerized and will be administered several times throughout the school year, they can provide faster feedback(反馈)to teachers.If these plans work out, It’ll turn the current testing system upside down.

One group,led by Florida,will be made up of 25 states and the District of Columbia.The group was awarded $170 million.The other group, whose membership over-laps the first,has31 states and is led by Washington.The group was given $160 million.Twelve of the 44 states are

participating in both groups but are expected eventually to choose one set of tests.

The two groups are supposed to work in a friendly competition,though their plans are very similar.Both groups will produce tests that rely heavily on technology and both groups’ tests will include so-called performance-based tasks,designed to mirror complex,real-world situations.

In performance-based tasks,students are given a problem-they could be told, for example, to suppose they are a mayor who needs to reduce a city’s pollution—and must write about how they would solve the problem.

The new tests could be useful to teachers by giving them information on what their students are learning, but it might also require some mid-course adjustments.

Over the past decade, the federal No Child Left Behind law has emphasized helping low-achieving students improve their basic reading and math by encouraging states to produce tests that measure relatively low-1evel skills. Although the Bush-era law is still on the books, two

years of Obama administration policy have been leading schools in new directions.   

小题1:. . What is the main idea of this passage?

A.Obama’s education policy takes the lead.

B.A computer-based testing system is adopted.

C.American education system has been changed.

D.Experts are reinventing the student testing system.小题2:.  Why are multiple-choice exams to be given up?

A.Because they are not computer-based.

B.Because they can’t test students’ higher-order skills.

C.Because they can’t provide proper feedback for teachers.

D.Because they can’t test students’ general reading ability.小题3:.  The underlined part in Para. 4 probably means________.

A.the two groups have some shared members

B.the other group is more demanding than the first

C.the groups have different tasks of their own

D.the other group does better than the first group in the task小题4:.  According to the passage, performance-based tasks may refer to tasks that______.

A.are related to real-world problems

B.have to be performed in an imaginary world

C.teach us theories through complex problems

D.can only be completed by relying heavily on technology小题5:. . From the last paragraph, we can infer that_________.

A.the No child Left Behind policy is not helpful

B.the Obama administration’s policy is highly praised

C.the two policies both emphasize math and reading abilities

D.the two policies both emphasize the development of practical skills