问题 选择题

关于电压及电压表,下列说法正确的是(  )

A.有电压时也可能没有电流

B.有电压就一定能形成电流

C.电压表不能直接接在电源两极上

D.电压表使用时要尽量选用大量程以免损坏

答案

A、有电压,但电路中可能没有电流,因持续电流的产生除了要有电压外,还必须有闭合的电路;故A正确,符合题意;

B、电压是形成电流的条件之一,要产生电流,还要有闭合的电路;故B错误;不符合题意;

C、电压表可以直接测量电源电压,故C选项错误;不符合题意;

D、为了确保不烧坏电压表,应该先选用大量程,若量程太大时,没有超过小量程,则改用小量程,故D选项错误;不符合题意.

故选A.

阅读理解

Reading comprehension.

     Almost a decade ago, the federal government dropped $100 million for an Earth-monitoring satellite that

never made it into space. Today it sits in a closet in Maryland. Cost to taxpayers for storing it: $1 million a

year. And that's just what's hiding in one closet. Who knows what's in the rest of them?

     Because we think the government should be held to at least the same standards as a publicly traded

company, and because as taxpayers, we're America's shareholders, we performed an audit (财务检查) of

sorts of the federal books. We're not economists, but we do have common sense. We tried to be apolitical

(无关政治的) and got help from Congressional staffers from both parties, as well as various watchdog

groups and agencies. In the end, we found that the federal government wastes nearly $1 trillion every year.

     That's roughly equal to the amount collected annually by the Internal Revenue Service in personal income

taxes. Put another way, it's also equal to about one-third of the country's $2.9 trillion total annual budget.

And reclaiming that lost trillion (三十亿) could help wipe out the country's annual budget deficit (赤字),

improve education, and provide health insurance for those who don't have it.

     So how do you define "waste"? David Walker of the Government Accountability Office (GAO), a federal

watchdog agency, calls it "the government's failure to give taxpayers the most for their money." For our part,

we used the kind of household test you would use on a piece of meat sitting in your refrigerator: If it smells

rotten, it's waste. And there is plenty to sniff out (闻出). Our government regularly pays for products and

services it never gets, wildly overpays companies to do things it could do more cheaply itself, loses money

completely due to lax (松弛的) accounting and oversight, fails to collect what it's owed, and put forward

unnecessary programs.

     How exactly does the federal government waste your hard-earned tax dollars? We've identified what we

consider ten of the worst ways.

1. The underlined sentence in Paragraph l really means _____. [ ]

A. there are many other closets

B. there are some other satellites

C. there is something else in the closets

D. the waste may be quite amazing

2. Which of the following statements may be right? [ ]

A. The country's annual budget is usually decided by the public.

B. The government failed in launching the satellite.

C. The government is only wasting money in space experiments.

D. The amount collected annually in personal income taxes is equal to the country's budget.

3. Which of the following can best describe the feeling of the author? [ ]

A. Annoyed. 

B. Calm

C. Surprised

D. Not concerned.

4. The best title for the passage would be _____. [ ]

A. Protecting Our Rights!

B. Our Country Is In Danger!

C. The Government Is Wasting Our Tax Dollars!

D. How to Prevent Government from Wasting Money!

5. What might be talked about if the passage is continued? [ ]

A. Listing how the government is wasting taxes.

B. Presenting people's feelings against the government's wasting taxes.

C. Giving suggestion to help the government solve the financial problem.

D. The government's taking some steps to stop wasting taxes.

单项选择题